Description
In the Linux kernel, the following vulnerability has been resolved: netfilter: nf_conntrack_h323: fix OOB read in decode_choice() In decode_choice(), the boundary check before get_len() uses the variable `len`, which is still 0 from its initialization at the top of the function: unsigned int type, ext, len = 0; ... if (ext || (son->attr & OPEN)) { BYTE_ALIGN(bs); if (nf_h323_error_boundary(bs, len, 0)) /* len is 0 here */ return H323_ERROR_BOUND; len = get_len(bs); /* OOB read */ When the bitstream is exactly consumed (bs->cur == bs->end), the check nf_h323_error_boundary(bs, 0, 0) evaluates to (bs->cur + 0 > bs->end), which is false. The subsequent get_len() call then dereferences *bs->cur++, reading 1 byte past the end of the buffer. If that byte has bit 7 set, get_len() reads a second byte as well. This can be triggered remotely by sending a crafted Q.931 SETUP message with a User-User Information Element containing exactly 2 bytes of PER-encoded data ({0x08, 0x00}) to port 1720 through a firewall with the nf_conntrack_h323 helper active. The decoder fully consumes the PER buffer before reaching this code path, resulting in a 1-2 byte heap-buffer-overflow read confirmed by AddressSanitizer. Fix this by checking for 2 bytes (the maximum that get_len() may read) instead of the uninitialized `len`. This matches the pattern used at every other get_len() call site in the same file, where the caller checks for 2 bytes of available data before calling get_len().
Product status
ec8a8f3c31ddef0a7d9626c4b8a4baa30f3b80aa (git) before bcb50aa0b8f2b74a9fe5a1c7bee6f2657a288041
ec8a8f3c31ddef0a7d9626c4b8a4baa30f3b80aa (git) before 2a3aac4205e7d2f1aca2e3827de8cdd517d36c4a
ec8a8f3c31ddef0a7d9626c4b8a4baa30f3b80aa (git) before 81f2fc5b0d0cf4696146f00f837596d10b92dead
ec8a8f3c31ddef0a7d9626c4b8a4baa30f3b80aa (git) before 7ef82863d42261817a6394c6c881bd6757a70f16
ec8a8f3c31ddef0a7d9626c4b8a4baa30f3b80aa (git) before 53d32735d77ab56cc3fc7bd53a7d099418f19be1
ec8a8f3c31ddef0a7d9626c4b8a4baa30f3b80aa (git) before f0a83d0a4b7c127d32ac06d607a9214937716129
ec8a8f3c31ddef0a7d9626c4b8a4baa30f3b80aa (git) before 35f1943d242e1b9f0b6e91c0c93bfb293a9f8224
ec8a8f3c31ddef0a7d9626c4b8a4baa30f3b80aa (git) before baed0d9ba91d4f390da12d5039128ee897253d60
4.15
Any version before 4.15
5.10.252 (semver)
5.15.202 (semver)
6.1.165 (semver)
6.6.128 (semver)
6.12.75 (semver)
6.18.16 (semver)
6.19.6 (semver)
7.0 (original_commit_for_fix)
References
git.kernel.org/...c/bcb50aa0b8f2b74a9fe5a1c7bee6f2657a288041
git.kernel.org/...c/2a3aac4205e7d2f1aca2e3827de8cdd517d36c4a
git.kernel.org/...c/81f2fc5b0d0cf4696146f00f837596d10b92dead
git.kernel.org/...c/7ef82863d42261817a6394c6c881bd6757a70f16
git.kernel.org/...c/53d32735d77ab56cc3fc7bd53a7d099418f19be1
git.kernel.org/...c/f0a83d0a4b7c127d32ac06d607a9214937716129
git.kernel.org/...c/35f1943d242e1b9f0b6e91c0c93bfb293a9f8224
git.kernel.org/...c/baed0d9ba91d4f390da12d5039128ee897253d60