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* executor: disallow O_CREAT in syz_open_devFlorent Revest2025-11-141-1/+1
| | | | | | | | | | I can't think of a valid reason to create nodes under /dev/ if they don't already exist. On systems where /dev/ isn't backed by a virtual/temp file system, O_CREAT lets syzkaller create persistent files on disk and may unnecessarily clutter or fill the disk with files that have nothing to do with the intended syscall descriptions.
* prog: fix syz_kfuzztest_run allocation strategyEthan Graham2025-09-221-4/+4
| | | | | | | | | | | | | | | | | | | | Previously, the generated KFuzzTest programs were reusing the address of the top-level input struct. A problem could arise when the encoded blob is large and overflows into another allocated region - this certainly happens in the case where the input struct points to some large char buffer, for example. While this wasn't directly a problem, it could lead to racy behavior when running KFuzzTest targets concurrently. To fix this, we now introduce an additional buffer parameter into syz_kfuzztest_run that is as big as the maximum accepted input size in the KFuzzTest kernel code. When this buffer is allocated, we ensure that we have some allocated space in the program that can hold the entire encoded input. This works in practice, but has not been tested with concurrent KFuzzTest executions yet.
* kfuzztest: introduce syz_kfuzztest_run pseudo-syscallEthan Graham2025-09-221-0/+54
| | | | | | | | | | | | | Add syz_kfuzztest_run pseudo-syscall, KFuzzTest attribute, and encoding logic. KFuzzTest targets, which are invoked in the executor with the new syz_kfuzztest_run pseudo-syscall, require specialized encoding. To differentiate KFuzzTest calls from standard syzkaller calls, we introduce a new attribute called KFuzzTest or "kfuzz_test" in syzkaller descriptions that can be used to annotate calls. Signed-off-by: Ethan Graham <ethangraham@google.com>
* executor: sys/linux/: pkg/runtest: pkg/vminfo: add syz_kvm_assert_syzos_kvm_exitAlexander Potapenko2025-09-191-1/+1
| | | | Implement a pseudo-syscall to check the value of kvm_run.exit_reason
* executor: neutralize errors=panic for gfs2 mountsAleksandr Nogikh2025-07-171-0/+3
| | | | | | | Append errors=withdraw to the mount options so that gfs2 withdrawals don't lead to kernel panics. Closes #6189.
* executor: linux: make syz_open_dev comment more correctFlorent Revest2025-06-041-1/+1
| | | | | | The logic in that branch of the code relies on replacing # characters with numbers. There's a comment in the code which shows a clarifying example but it misses the # which I found mildly confusing.
* executor: linux: fix syz_open_dev virtual file names rangeFlorent Revest2025-06-041-2/+3
| | | | | | | | | | | | | | | | | | | | | | | | We noticed that syzkaller left some files with fairly unusual file names under /dev. Eg: ---------- 1 root root 0 May 30 14:42 vcs- ---------- 1 root root 0 May 30 14:48 vcs. ---------- 1 root root 136317631 May 30 14:42 vcs' ---------- 1 root root 0 May 30 14:48 vcs( ---------- 1 root root 0 May 30 14:43 vcs) ---------- 1 root root 0 May 30 14:43 vcs* ---------- 1 root root 136317633 May 30 14:46 vcs+ Funnily enough the characters after "vcs" are always within the '0'-10 to '0' ASCII range. We noticed that the syz_open_dev logic uses a modulo 10 on a signed number (the volatile long a1 argument) and in C the modulo of a negative number stays negative, so the result of this operation is in the '0'-10 to '0'+10 range. This is in turn casted to a char which is also signed and doesn't fix the glitch. By casting a1 to an unsigned long first, this keeps the result of the modulo operation signed and therefore the virtual file name suffix a number.
* all: format with clang-format-20Aleksandr Nogikh2025-04-241-127/+124
| | | | The tests began to fail after pushing the new env container.
* executor/kvm: add x86-64 SYZOS fuzzerMarios Pomonis2025-04-231-0/+2
| | | | | | This commit adds the actual SyzOS fuzzer for x86-64 and a small test. It also updates some necessary parts of the ARM version and adds some glue for i386.
* executor: mount /syz-inputs dir to fuzzing sandboxNick Biryulin2025-01-281-0/+10
| | | | | | | | Syzkaller allows user to specify filepath arguments in syscalls via globs. However, on linux, you are effectivly limited to some /sys and /dev paths due to sandboxing. With this change, user can supply their custom fuzzing artifacts to /syz-inputs to use those in globs. They are mounted read-only to increase reproducibility.
* executor: pkg/vminfo: sys/linux: arm64: implement syz_kvm_assert_reg()Alexander Potapenko2024-12-181-1/+1
| | | | Add a pseudo-syscall to assert on register values.
* executor: mount gadgetfsDmitry Vyukov2024-12-111-0/+17
| | | | We can reach it at least with automatic descriptions.
* pkg/vminfo: sys/linux: executor: define syz_kvm_assert_syzos_uexit()Alexander Potapenko2024-12-111-1/+1
| | | | | The new pseudo-syscall will serve as a test assertion, checking the uexit return value. This is going to help us validate SyzOS code.
* sys/linux: updated fuse fs specificationsSablin Viacheslav2024-11-291-0/+7
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* sys/linux: move some ARM-specific descriptions to a separate fileAlexander Potapenko2024-11-261-18/+0
| | | | | | | | | | | | | | This is done to solve a particular test failure running: $ tools/syz-env go test ./prog -run TestSpecialStructs , which failed on PPC64, because prog/rand.go instanciated a call to syz_kvm_setup_syzos_vm(), which requested too much memory (1024 pages) from the allocator (PPC64 uses 64k pages, so the number of available pages is lower). On the other hand, factoring out syzos-related descriptions is probably a nice thing to do anyway.
* executor: arm64: sys/linux: allocate 1024 pages for guest address spaceAlexander Potapenko2024-11-261-1/+1
| | | | | | | Pass 1024 pages of memory to both syz_kvm_setup_syzos_vm() and syz_kvm_setup_cpu$arm64() to make sure that: - there is enough memory for guest allocations (e.g. ITS pages) - host can tamper with that memory, provoking more bugs
* executor: check ppid after setting PR_SET_PDEATHSIG for sandbox processDmitry Vyukov2024-10-241-0/+4
| | | | This helps to avoid leaking processes when killing races with PR_SET_PDEATHSIG.
* executor: don't create new session for sandbox processDmitry Vyukov2024-10-241-1/+0
| | | | | | | | It's unclear why we need a new session. Sessions group process groups, but we don't use that. Setsid also creates a new process group, but we don't kill this process group, so also unclear why this is needed.
* executor: fix mounting of debugfs/smackfs/fusectl/binfmt_miscDmitry Vyukov2024-09-271-9/+14
| | | | | | | | All these broke when we started mounting new tmpfs for sandbox=root. Some are not mounted at all, some are mounted in the outer root and are not accessible from the new root. Mount then inside of the new root tmpfs. Other file systems (binderfs, cgroups) seem to be ok.
* executor: arm64: sys/linux: implement syz_kvm_setup_syzos_vm and ↵Alexander Potapenko2024-09-251-1/+13
| | | | | | | | | | | | | | | | | | | | | | | syz_kvm_add_vcpu The old syz_kvm_setup_cpu() API mixed together VM and VCPU setup, making it harder to create and fuzz two VCPUs in the same VM. Introduce two new pseudo-syscalls, syz_kvm_setup_syzos_vm() and syz_kvm_add_vcpu(), that will simplify this task. syz_kvm_setup_syzos_vm() takes a VM file descriptor, performs VM setup (allocates guest memory and installs SYZOS code into it) and returns a new kvm_syz_vm resource, which is in fact a pointer to `struct kvm_syz_vm` encapsulating VM-specific data in the C code. syz_kvm_add_vcpu() takes the VM ID denoted by kvm_syz_vm and creates a new VCPU within that VM with a proper CPU number. It then stores the fuzzer-supplied SYZOS API sequence into the corresponding part (indexed by CPU number) of the VM memory slot, and sets up the CPU registers to interpret that sequence. The new pseudo-syscall let the fuzzer create independent CPUs that run different code sequences without interfering with each other.
* sys/linux: add syz_create_resourceDmitry Vyukov2024-09-191-0/+13
| | | | | | | | syz_create_resource allows to turn any value into a resource. Improve binfmt descriptions using syz_create_resource: we need to pass the same file name to write syscalls and execve. Use syz_create_resource to improve binfmt descriptions.
* executor: fix mounting of binfmt_miscDmitry Vyukov2024-09-191-1/+2
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* executor: pkg/vminfo: sys/linux: define syz_kvm_vgic_v3_setupAlexander Potapenko2024-09-031-2/+8
| | | | | The new pseudo-syscall sets up VGICv3 IRQ controller on the host. That still requires guest setup code, which will be submitted separately.
* executor: protect kcov/output regions with pkeysDmitry Vyukov2024-08-161-0/+6
| | | | | | | Protect KCOV regions with pkeys if they are available. Protect output region with pkeys in snapshot mode. Snapshot mode is especially sensitive to output buffer corruption since its location is not randomized.
* executor: increase kExtraCoverSize to 1024kAndrey Konovalov2024-07-231-1/+1
| | | | | | | | | | | | | | | Running the vusb_ath9k runtest (with [1] and [2] applied) produces ~100k of extra coverage, which is somewhat close to the current 256k limit. A more complicated program might produce more extra coverage and overflow the coverage buffer. Increase kExtraCoverSize to 1024k. As the extra coverage buffer is maintained per-executor and not per-thread, the total increase of the coverage mapping is ~9%, which is not too bad. [1] https://lore.kernel.org/all/eaf54b8634970b73552dcd38bf9be6ef55238c10.1718092070.git.dvyukov@google.com/ [2] https://lore.kernel.org/all/20240722223726.194658-1-andrey.konovalov@linux.dev/T/#u
* executor: fix setup of cad_pidDmitry Vyukov2024-07-161-5/+20
| | | | | | | cad_pid must not point to a persistent runner process, b/c it will be killed on ctrl+alt+del. Fixes #5027
* executor: set `source` for the proc mountAndrei Vagin2024-07-031-1/+1
| | | | | | | | | | mount() in gVisor returns EFAULT if source is NULL. It is a gVisor issue and we will fix it. Let's explicitly sets a string source for the proc mount to unblock gVisor jobs. The source string will additionally be useful for troubleshooting mount-related problems in the future, because it is shown in /prod/pid/mountinfo. Signed-off-by: Andrei Vagin <avagin@google.com>
* executor: linux: bump fs.mount-max to 100000Alexander Potapenko2024-07-031-0/+3
| | | | | | | Android sets fs.mount-max to 100, making it impossible to create new chroots. Relax the limit, setting it to a value used on desktops. Tracking bug: https://github.com/google/syzkaller/issues/4972
* executor: linux: chroot into tmpfs with sandbox=noneAlexander Potapenko2024-07-021-50/+63
| | | | | | | | | | | To prevent the executor from accidentally making the whole root file system immutable (which breaks fuzzing), modify sandbox=none to create a tmpfs mount and chroot into it before executing programs in a process. According to `syz-manager -mode=smoke-test`, the number of enabled syscalls on x86 doesn't change with this patch. Fixes #4939, #2933, #971.
* executor/linux: fix compilation error with old compilersPavel Skripkin2024-06-251-1/+8
| | | | | | | | | | | | | | | | | | | | My gcc-10 in testing vm compainls during reproducer [0] build with following error: rep.c: In function ‘remove_dir’: rep.c:662:3: error: a label can only be part of a statement and a declaration is not a statement 662 | const int umount_flags = MNT_FORCE | UMOUNT_NOFOLLOW; | ^~~~~ Label followed by declaration is C23 extension, so only new compilers support it. Fix it by moving declaration above `retry` label and put unused attribute to suppress possible warning. [0] https://syzkaller.appspot.com/bug?extid=dcc068159182a4c31ca3 Signed-off-by: Pavel Skripkin <paskripkin@gmail.com>
* executor: handle errors from netlink_query_family_idCameron Finucane2024-06-171-0/+17
| | | | | There were some cases where the return value was not checked, allowing errors to propagate. This fixes them to return early with a message.
* docs: remove mentions of strconstDmitry Vyukov2024-06-111-1/+1
| | | | strconst["foo"] was replaced by ptr[in, string["foo"]].
* executor: use close_range if availableDmitry Vyukov2024-06-101-0/+5
| | | | Close_range is faster.
* executor: rework feature setupDmitry Vyukov2024-06-031-83/+76
| | | | | | | | | | | | | Return failure reason from setup functions rather than crash. This will provide better error messages, but also allow setup w/o creating subprocesses which will be needed when we combine fuzzer and executor. Also close all resources created during setup. This is also useful for in-process setup, but also should improve chances of reproducing a bug with C reproducer. Currently leaked file descriptors may disturb repro execution (e.g. it may act on a wrong fd).
* executor: setup binfmt_mist only if it has been mountedAndrei Vagin2024-05-091-0/+1
| | | | | | | gVisor doesn't implement binfmt file system. Fixes: 229488b413d4 ("executor: consistently fail on feature setup") Signed-off-by: Andrei Vagin <avagin@google.com>
* executor: consistently fail on feature setupDmitry Vyukov2024-05-071-42/+41
| | | | | | Currently we fail in some cases, but ignore errors in other cases. Consistently fail when feature setup fails. This will be required for relying on setup failure to detect feature presence.
* executor: ignore EBADF when reading tunDmitry Vyukov2024-04-161-1/+2
| | | | | | | | | | | | Fuzzer managed to do: executing program 0: ... close_range(r5, 0xffffffffffffffff, 0x0) ... SYZFATAL: executor 0 failed 11 times: executor 0: exit status 67 SYZFAIL: tun read failed (errno 9: Bad file descriptor)
* executor: ignore socketpair error in syz_usbip_server_initDmitry Vyukov2024-04-161-2/+5
| | | | | | | | | | | | | | Fuzzer managed to do: executing program 4: ... prlimit64(0x0, 0x7, &(0x7f0000000000), 0x0) ... syz_usbip_server_init(0x3) ... SYZFATAL: executor 4 failed 11 times: executor 4: exit status 67 SYZFAIL: syz_usbip_server_init: socketpair failed (errno 24: Too many open files)
* executor: cleanup mounts with MNT_FORCEAleksandr Nogikh2024-04-101-4/+9
| | | | | | | | | | Starting from v6.9, we can no longer reuse a loop device while some filesystem is mounted on it. It conflicts with the MNT_DETACH approach we were previously using. Let's umount synchronously instead, but also with a MNT_FORCE flag to abort potentially long graceful cleanup operations. We don't need them for the filesystems mounted only for fuzzing purposes.
* executor: ignore ENOENT for socket callsDmitry Vyukov2024-04-021-0/+12
| | | | | | Don't treat ENOENT from socket call as fatal. Fuzzer manages to make all socket calls for a particular protocol fail using NLBL_MGMT_C_REMOVE netlink function.
* executor: temporarily disable IORING_SETUP_CQE32 and IORING_SETUP_SQE128Alexander Potapenko2024-03-051-1/+5
| | | | | | | | | | IORING_SETUP_CQE32 and IORING_SETUP_SQE128 may lead to incorrect assumptions about the ring buffer size, causing the kernel to write outside of the mapped memory, smashing whatever follows it. This is a hotfix for https://github.com/google/syzkaller/issues/4531 that will stop the ci-upstream-gce-arm64 from generating random coverage.
* executor: don't fail on setns() in pseudo syscallsAleksandr Nogikh2024-02-081-4/+10
| | | | | | | The fd may be closed by an async close() call, it's not a reason to report a failure. Reported-by: Andrei Vagin <avagin@google.com>
* executor: don't hold a loop device fdAleksandr Nogikh2024-01-121-5/+26
| | | | | | When BLK_DEV_WRITE_MOUNTED is enabled, the kernel treats the loopfd reference as a writer and does not let us issue mount() calls over the same block device.
* executor: prevent netlink_send_ext with dofail=trueAleksandr Nogikh2024-01-051-0/+7
| | | | | This should never be happening during fuzzing. Otherwise we let syz-executor silently crash and restart insane number of times.
* syz-executor: don't fail on netlink errors during fuzzingAleksandr Nogikh2024-01-051-21/+23
| | | | | | During fuzzing, it's expected that certain operations might return errors. Don't abort the whole syz-executor process in this case, this is too expensive.
* executor: introduce syz_pidfd_open()Aleksandr Nogikh2023-12-191-0/+18
| | | | | | | | | | | This kernel interface provides access to fds of other processes, which is readily abused by the fuzzer to mangle parent syz-executor fds. Pid=1 is the parent syz-executor process when PID namespace is created. Sanitize it in the new syz_pidfd_open() pseudo-syscall. We could not patch the argument in sys/linux/init.go because the first argument is a resource.
* sys/linux, pkg/host, executor: add NVMe-oF/TCP subsystem supportAlon Zahavi2023-12-071-2/+46
| | | | | Add new pseudo-syscall for creating a socket in init netns and connecting to NVMe-oF/TCP server on 127.0.0.1:4420. Also add descriptions for NVMe-oF/TCP.
* sys/io_uring, executor/common_linux: remove sqes_index in syz_io_uring_submitDylan Yudaken2023-07-301-17/+12
| | | | | | | | This parameter barely increases coverage since the tail is always set to the entry that is written, but it does increase the complexity of the api and seems to reduce coverage when I run it locally. Remove it.
* sys/linux/io_uring, executor/common_linux: fix io_uring segfaultDylan Yudaken2023-07-301-9/+7
| | | | | | | | | | In Linux 6.4+ it is not allowed to provide a vma to mmap(2) [1]. Change the API to request the address from the Kernel. Note I do not know why this was done in the first place, but it seems not to be useful. [1]: https://github.com/torvalds/linux/commit/d808459b2e31bd5123a14258a7a529995db974c8
* executor: include missing linux/falloc.hKhem Raj2023-06-201-0/+1
| | | | | | | | | | | | | | Its needed for FALLOC_FL_ZERO_RANGE which needs this header, it works with glibc because fcntl.h includes this header indirectly, however the failure comes to fore with musl C library where this header is not included indirectly by other system headers, therefore include it as required. Fixes In file included from executor/common.h:505: executor/common_linux.h:5604:16: error: use of undeclared identifier 'FALLOC_FL_ZERO_RANGE' fallocate(fd, FALLOC_FL_ZERO_RANGE, 0, SWAP_FILE_SIZE); ^
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