| Commit message (Collapse) | Author | Age | Files | Lines |
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Like we already do on ARM, use prime numbers multiplied by 10 for
SYZOS API IDs to prevent the compiler from emitting a jump table in
guest_main().
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Append errors=withdraw to the mount options so that gfs2 withdrawals
don't lead to kernel panics.
Closes #6189.
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It used to fail because we cannot mmap 0 bytes.
Closes #6148.
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We expect these commands to reach some NV coverage
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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.
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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.
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This commit adds support for CPUID instructions on AMD64. It also adds a
relevant test.
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When compiling SYZOS into the executor binary, the compiler often
attempts to emit a jump table, putting it into the data section
of the executor. SYZOS is unable to access that data and crashes.
Use primes multiplied by 10 to defeat the compiler's heuristics
for jump table emission.
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clang-tidy-20 generates many more failures, many of which are in the
flartrpc library. Let's disable clang-analyzer-optin.core.EnumCastOutOfRange
for now.
It also complained about PROT_EXEC in the executor, but that is
necessary to support syz_execute_func().
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The tests began to fail after pushing the new env container.
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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.
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This commit prepares adding the X86-64 SYZOS by declaring the relevant
functions, updating their ARM64 versions and adding placeholders.
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* Fixes a bug when setting up a 64-bit guest by making the bit
manipulation macros produce unsigned long long: To create a VCPU that
has paging enabled, one needs to set the CR0.PE and CR0.PG bits in
CR0. The latter is problematic when setting up a 64-bit guest since if
the macro is not using 1ULL, it sign extends the output (in 64-bit
mode the control registers are extended to 64-bits with some of the
CR0[32:63] bits reserved). This results in either failing the
KVM_SET_SREGS ioctl (in newer kernel versions) or just failing the
KVM_RUN ioctl with EXIT_REASON_INVALID_STATE.
* Moved the bit manipulation definitions from the amd64 specific to the generic
kvm header to consolidate them with the already existing ones.
Prefixed them with X86_ to avoid confusion.
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The error handling for the setsid() call in sandbox_common() requires
it. Without it, some csource builds fail.
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During machine checks, syzkaller will execute calls with coverage
disabled, in which case per-thread coverage structures are zeroed out.
write_output() will temporarily map the coverage data as writeable via
CoverAccessScope, whether or not cover is enabled. In effect,
write_output() may trigger a call mprotect(0, kCoverSize, PROT_RW).
On FreeBSD, mprotect() silently ignores unmapped regions, so this does
not result in an error. In fact, kCoverSize is now large enough that
this ends up removing the eXecute bit from part of syz-executor's text
region.
Make CoverAccessScope a no-op if coverage is not enabled. Modify BSD
cover_protect() and cover_unprotect() to fail if invoked when coverage
is disabled.
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As we figured out in #5805, syz-manager treats random incoming RPC
connections as trusted, and will crash if a non-executor client sends
an invalid packet to it.
To address this issue, we introduce another stage of handshake, which
includes a cookie exchange:
- upon connection from an executor, the manager sends a ConnectHello RPC
message to it, which contains a random 64-bit cookie;
- the executor calculates a hash of that cookie and includes it into
its ConnectRequest together with the other information;
- before checking the validity of ConnectRequest, the manager ensures
client sanity (passed ID didn't change, hashed cookie has the expected
value)
We deliberately pick a random cookie instead of a magic number: if the
fuzzer somehow learns to send packets to the manager, we don't want it to
crash multiple managers on the same machine.
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Some environments don't define MAP_FIXED_NOREPLACE.
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MAP_FIXED_NOREPLACE allows to fail early if we happened to overlap with
an existing memory mapping. It should help detects bugs #5674 at an
earlier stage, before it led to memory corruptions.
MAP_FIXED_NOREPLACE is supported from Linux 4.17, which is okay for all
syzkaller use cases on syzbot.
There's no such option for some of the supported OSes, so set it
depending on the configuration we're building for.
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Proper glob resolution is required for fuzzing.
If it times out, it does so silently, and fuzzing dictionary will be smaller then expected, without any obvious errors.
Given that, it makes sense to increase glob timeouts.
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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.
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Add support for the MRS instruction in a similar manner to MSR.
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Make sure operands passed to 64-bit MOV, MSR and MRS instructions are
actually 64-bit.
This fixes compiler warnings in certain build configurations.
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Add a pseudo-syscall to assert on register values.
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In some build environments (notably Yocto), syzkaller host and target
binaries end up in separate packages for each built architecture, which
are then shipped with the respective image/SDK.
Add the "Execprog/ExecutorBinOnTarget" and "StraceBinOnTarget" options
to the manager config, which when set expects the respective binaries to
be shipped with the target image and does not attempt to copy them from
the host.
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We can reach it at least with automatic descriptions.
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We query globs for 2 reasons:
1. Expand glob types in syscall descriptions.
2. Dynamic file probing for automatic descriptions generation.
In both of these contexts are are interested in files
that will be present during test program execution
(rather than normal unsandboxed execution).
For example, some files may not be accessible to test programs
after pivot root. On the other hand, we create and link
some additional files for the test program that don't
normally exist.
Add a new request type for querying of globs that are
executed in the test program context.
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The new pseudo-syscall will serve as a test assertion, checking the uexit
return value. This is going to help us validate SyzOS code.
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When running syscalls asynchronously, syz_kvm_add_vcpu() sometimes
receives a zero VM handle, on which it then crashes.
Check for the zero value to ensure stability of the tests in sys/linux/tests.
Also make sure to set errno for the pseudo-syscall in the cases where it's not
done by the underlying syscalls.
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We missed that step for snapshot mode.
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Make sure regressions in guest code validation are reported during testing
rather than fuzzing.
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Glob() doesn't work on 32-bit ARM when run on a 64-bit system under QEMU:
https://gitlab.com/qemu-project/qemu/-/issues/263
Not sure whether this is specific to tests running under qemu-user, or
the ARM32 executor in the wild as well.
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Prevent the compiler from generating a jump table by replacing a switch
with a series of if statements.
This is ugly, but lets us work around crashes caused by https://github.com/google/syzkaller/issues/5565
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Apply __attribute__((noinline)) to SyzOS API command handlers to prevent
overly optimizing them.
While at it, rearrange specifiers in guest function declarations
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Detect and report ADRP instructions in the linked binaries to avoid
crashes inside SyzOS.
See https://github.com/google/syzkaller/issues/5565 for more context.
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It's no longer needed.
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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.
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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
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In addition to the predefined ITS setup, let the guest execute different
ITS configuration commands in an attempt to trigger interesting interactions.
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The new API call implements basic setup of the ARM Interrupt Translation Service
for the given number of CPUs, virtual devices, and LPIs.
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There's no need to mask the IDs, and it actually doesn't work for LPIs.
Also add more comments.
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Currently we write coverage backwards.
This is visible e.g. when running syz-execprog -coverfile,
and in the manager raw cover mode.
Write it in the right order.
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Don't follow symlinks when globbing.
It's haarmful for both files and dirs
(see the added comment for details).
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The coverage buffer frequently overflows.
We cannot increase it radically b/c they consume lots of memory
(num procs x num kcovs x buffer size) and lead to OOM kills
(at least with 8 procs and 2GB KASAN VM).
So increase it 2x and slightly reduce number of threads/kcov descriptors.
However, in snapshot mode we can be more aggressive (only 1 proc).
This reduces number of overflows by ~~2-4x depending on syscall.
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If the overflows happen often, it's bad.
Add visibility into this.
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After 9fc8fe026baa ("executor: better handling for hanged test
processes"), yz-executor's responses may reference procids outside of
the [0;procs] range.
If procids are no longer dense on the syz-executor side, we cannot rely
on this check in pkg/rpcserver:
```
if avoid == (uint64(1)<<runner.procs)-1 {
avoid = 0
}
```
Signed-off-by: Andrei Vagin <avagin@google.com>
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