We would read (-1), and then add 1 to it, call message_peek_body(..., 0, ...),
and when trying to make use of the data.
The fuzzer test case is just for one site, but they all look similar.
v2: fix two UINT8_MAX/UINT32_MAX mismatches founds by LGTM
We copied part of the string into a buffer that was off by two.
If the element signature had length one, we'd copy 0 bytes and crash when
looking at the "first" byte. Otherwise, we would crash because strncpy would
not terminate the string.
This is similar to the grandparent commit 'fix calculation of offsets table',
except that now the change is for array elements. Same story as before: we need
to make sure that the offsets increase enough taking alignment into account.
While at it, rename 'p' to 'previous' to match similar code in other places.
The offsets specify the ends of variable length data. We would trust the
incoming data, putting the offsets specified in our message
into the offsets tables after doing some superficial verification.
But when actually reading the data we apply alignment, so we would take
the previous offset, align it, making it bigger then current offset, and
then we'd try to read data of negative length.
In the attached example, the message specifies the following offsets:
[1, 4]
but the alignment of those items is
[1, 8]
so we'd calculate the second item as starting at 8 and ending at 4.
The alternative would be to treat gvariant and !gvariant messages differently.
But this is a problem because we check signatures is variuos places before we
have an actual message, for example in sd_bus_add_object_vtable(). It seems
better to treat things consistent (i.e. follow the lowest common denominator)
and disallow empty structures everywhere.
We didn't free one of the fields in two of the places.
$ valgrind --show-leak-kinds=all --leak-check=full \
build/fuzz-bus-message \
test/fuzz/fuzz-bus-message/leak-c09c0e2256d43bc5e2d02748c8d8760e7bc25d20
...
==14457== HEAP SUMMARY:
==14457== in use at exit: 3 bytes in 1 blocks
==14457== total heap usage: 509 allocs, 508 frees, 51,016 bytes allocated
==14457==
==14457== 3 bytes in 1 blocks are definitely lost in loss record 1 of 1
==14457== at 0x4C2EBAB: malloc (vg_replace_malloc.c:299)
==14457== by 0x53AFE79: strndup (in /usr/lib64/libc-2.27.so)
==14457== by 0x4F52EB8: free_and_strndup (string-util.c:1039)
==14457== by 0x4F8E1AB: sd_bus_message_peek_type (bus-message.c:4193)
==14457== by 0x4F76CB5: bus_message_dump (bus-dump.c:144)
==14457== by 0x108F12: LLVMFuzzerTestOneInput (fuzz-bus-message.c:24)
==14457== by 0x1090F7: main (fuzz-main.c:34)
==14457==
==14457== LEAK SUMMARY:
==14457== definitely lost: 3 bytes in 1 blocks
v2: fix error in free_and_strndup()
When the orignal and copied message were the same, but shorter than specified
length l, memory read past the end of the buffer would be performed. A test
case is included: a string that had an embedded NUL ("q\0") is used to replace
"q".
v3: Fix one more bug in free_and_strndup and add tests.
v4: Some style fixed based on review, one more use of free_and_replace, and
make the tests more comprehensive.
318/365 fuzz-bus-message:crash-26bba7182dedc8848939931d9fcefcb7922f2e56:address OK 0.03 s
319/365 fuzz-bus-message:crash-29ed3c202e0ffade3cad42c8bbeb6cc68a21eb8e:address OK 0.03 s
320/365 fuzz-bus-message:crash-b88ad9ecf4aacf4a0caca5b5543953265367f084:address OK 0.03 s
321/365 fuzz-bus-message:crash-c1b37b4729b42c0c05b23cba4eed5d8102498a1e:address OK 0.03 s
322/365 fuzz-bus-message:crash-d8f3941c74219b4c03532c9b244d5ea539c61af5:address OK 0.03 s
323/365 fuzz-bus-message:crash-e1b811da5ca494e494b77c6bd8e1c2f2989425c5:address OK 0.03 s
324/365 fuzz-bus-message:leak-c09c0e2256d43bc5e2d02748c8d8760e7bc25d20:address OK 0.04 s
325/365 fuzz-bus-message:message1:address OK 0.03 s
326/365 fuzz-bus-message:timeout-08ee8f6446a4064db064e8e0b3d220147f7d0b5b:address OK 0.03 s
327/365 fuzz-dhcp-server:discover-existing:address OK 0.04 s
328/365 fuzz-dhcp-server:discover-new:address OK 0.03 s
329/365 fuzz-dhcp-server:release:address OK 0.04 s
330/365 fuzz-dhcp-server:request-existing:address OK 0.03 s
331/365 fuzz-dhcp-server:request-new:address OK 0.03 s
332/365 fuzz-dhcp-server:request-reboot:address OK 0.03 s
333/365 fuzz-dhcp-server:request-renew:address OK 0.03 s
334/365 fuzz-dns-packet:issue-7888:address OK 0.03 s
335/365 fuzz-dns-packet:oss-fuzz-5465:address OK 0.03 s
336/365 fuzz-journal-remote:crash-5a8f03d4c3a46fcded39527084f437e8e4b54b76:address OK 0.06 s
337/365 fuzz-journal-remote:crash-96dee870ea66d03e89ac321eee28ea63a9b9aa45:address OK 0.04 s
338/365 fuzz-journal-remote:invalid-ts.txt:address OK 0.04 s
339/365 fuzz-journal-remote:oss-fuzz-8659:address OK 0.06 s
340/365 fuzz-journal-remote:oss-fuzz-8686:address OK 0.04 s
341/365 fuzz-journal-remote:sample.txt:address OK 0.07 s
342/365 fuzz-unit-file:directives.service:address OK 0.03 s
343/365 fuzz-unit-file:empty.scope:address OK 0.04 s
344/365 fuzz-unit-file:machine.slice:address OK 0.03 s
345/365 fuzz-unit-file:oss-fuzz-6884:address OK 0.05 s
346/365 fuzz-unit-file:oss-fuzz-6885:address OK 0.03 s
347/365 fuzz-unit-file:oss-fuzz-6886:address OK 0.04 s
348/365 fuzz-unit-file:oss-fuzz-6892:address OK 0.03 s
349/365 fuzz-unit-file:oss-fuzz-6897:address OK 0.05 s
350/365 fuzz-unit-file:oss-fuzz-6897-evverx:address OK 0.04 s
351/365 fuzz-unit-file:oss-fuzz-6908:address OK 0.05 s
352/365 fuzz-unit-file:oss-fuzz-6917:address OK 0.06 s
353/365 fuzz-unit-file:oss-fuzz-6977:address OK 0.08 s
354/365 fuzz-unit-file:oss-fuzz-6977-unminimized:address OK 0.10 s
355/365 fuzz-unit-file:oss-fuzz-7004:address OK 0.03 s
356/365 fuzz-unit-file:oss-fuzz-8064:address OK 0.03 s
357/365 fuzz-unit-file:oss-fuzz-8827:address OK 0.50 s
358/365 fuzz-unit-file:proc-sys-fs-binfmt_misc.automount:address OK 0.03 s
359/365 fuzz-unit-file:syslog.socket:address OK 0.03 s
360/365 fuzz-unit-file:systemd-ask-password-console.path:address OK 0.03 s
361/365 fuzz-unit-file:systemd-machined.service:address OK 0.03 s
362/365 fuzz-unit-file:systemd-resolved.service:address OK 0.03 s
363/365 fuzz-unit-file:systemd-tmpfiles-clean.timer:address OK 0.03 s
364/365 fuzz-unit-file:timers.target:address OK 0.03 s
365/365 fuzz-unit-file:var-lib-machines.mount:address OK 0.04 s
This gives us slightly nicer coverage in the normal test run.
When in a git repo, git ls-files is used to get a list of files known to git.
This mirrors what update-man-rules does for man files. Only looking at files
known to git makes it easier to not forget to commit the test file to git,
and also makes bisecting easier if some files are left in repo.
When outside of a git repo, we expect to be unpacked from a tarball, so just
using all files reported by ls is OK.
There isn't really much need to keep them separate. Anything which is a good
corpus entry can be used as a smoke test, and anything which which is a
regression test can just as well be inserted into the corpus.
The only functional difference from this patch (apart from different paths in
output) is that the regression tests are now zipped together with the rest of
the corpus.
$ meson configure build -Dslow-tests=true && ninja -C build test
...
307/325 fuzz-dns-packet:issue-7888:address OK 0.06 s
308/325 fuzz-dns-packet:oss-fuzz-5465:address OK 0.04 s
309/325 fuzz-journal-remote:crash-5a8f03d4c3a46fcded39527084f437e8e4b54b76:address OK 0.07 s
310/325 fuzz-journal-remote:crash-96dee870ea66d03e89ac321eee28ea63a9b9aa45:address OK 0.05 s
311/325 fuzz-journal-remote:oss-fuzz-8659:address OK 0.05 s
312/325 fuzz-journal-remote:oss-fuzz-8686:address OK 0.07 s
313/325 fuzz-unit-file:oss-fuzz-6884:address OK 0.06 s
314/325 fuzz-unit-file:oss-fuzz-6885:address OK 0.05 s
315/325 fuzz-unit-file:oss-fuzz-6886:address OK 0.05 s
316/325 fuzz-unit-file:oss-fuzz-6892:address OK 0.05 s
317/325 fuzz-unit-file:oss-fuzz-6897:address OK 0.05 s
318/325 fuzz-unit-file:oss-fuzz-6897-evverx:address OK 0.06 s
319/325 fuzz-unit-file:oss-fuzz-6908:address OK 0.07 s
320/325 fuzz-unit-file:oss-fuzz-6917:address OK 0.07 s
321/325 fuzz-unit-file:oss-fuzz-6977:address OK 0.13 s
322/325 fuzz-unit-file:oss-fuzz-6977-unminimized:address OK 0.12 s
323/325 fuzz-unit-file:oss-fuzz-7004:address OK 0.05 s
324/325 fuzz-unit-file:oss-fuzz-8064:address OK 0.05 s
325/325 fuzz-unit-file:oss-fuzz-8827:address OK 0.52 s
Zbigniew Jędrzejewski-Szmek