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Diffstat (limited to 'results/classifier/qwen3:32b/output/syscall/833')
| -rw-r--r-- | results/classifier/qwen3:32b/output/syscall/833 | 45 |
1 files changed, 45 insertions, 0 deletions
diff --git a/results/classifier/qwen3:32b/output/syscall/833 b/results/classifier/qwen3:32b/output/syscall/833 new file mode 100644 index 000000000..a3ce6e4f0 --- /dev/null +++ b/results/classifier/qwen3:32b/output/syscall/833 @@ -0,0 +1,45 @@ + + + +linux-user: sendmsg fails to send messages without iov +Description of problem: +When run via qemu `sendmsg` fails to send messages which contain a zero length `iov` but _do_ contain ancillary data. This works fine on plain Linux. + +A practical example: the `ell` library relies on this for setting the IV on a kernel crypto (`AF_ALG`) socket: https://git.kernel.org/pub/scm/libs/ell/ell.git/tree/ell/cipher.c#n526 + +A message without data but only ancillary data is used to set the IV. +Steps to reproduce: +See [qemu_ancillary.c](/uploads/84ee20aa3b9178022847d6cd7fcf0048/qemu_ancillary.c) for a self contained testcase which sends two mesages (one with `msg_iovlen=0`, one with `msg_iovlen=1`). + +(Test case is to be considered GPL, as I've copied bits from `ell`) + +Native: +``` +$ strace -esendmsg ./a.out +sendmsg(6, {msg_name=NULL, msg_namelen=0, msg_iov=NULL, msg_iovlen=0, msg_control=[{cmsg_len=36, cmsg_level=SOL_ALG, cmsg_type=0x2}], msg_controllen=40, msg_flags=0}, 0) = 0 +sendmsg(6, {msg_name=NULL, msg_namelen=0, msg_iov=[{iov_base="\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0", iov_len=16}], msg_iovlen=1, msg_control=[{cmsg_len=36, cmsg_level=SOL_ALG, cmsg_type=0x2}], msg_controllen=40, msg_flags=0}, 0) = 16 ++++ exited with 0 +++ +``` + + +Qemu (observe missing sendmsg call): +``` +$ strace -esendmsg ~/debug/qemu/build/qemu-x86_64 ./a.out +sendmsg(6, {msg_name=NULL, msg_namelen=0, msg_iov=[{iov_base="\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0", iov_len=16}], msg_iovlen=1, msg_control=[{cmsg_len=36, cmsg_level=SOL_ALG, cmsg_type=0x2}], msg_controllen=40, msg_flags=0}, 0) = 16 ++++ exited with 0 +++ +``` + +For a practical reproducer: + +1. Compile and run `ell`'s `test-cipher` test case: + +``` +$ ~/debug/qemu/build/qemu-x86_64 ./unit/test-cipher +TEST: unsupported +TEST: aes +TEST: aes_ctr +test-cipher: unit/test-cipher.c:102: test_aes_ctr: Assertion `!r' failed. +Aborted (core dumped) +``` + +A strace will look similar. |