CVE-2026-89783xfrm6: fix out-of-bounds write in xfrm6_input_addr() when secpath is full

Official description

In the Linux kernel, the following vulnerability has been resolved: xfrm6: fix out-of-bounds write in xfrm6_input_addr() when secpath is full The depth check in xfrm6_input_addr() is off by one: if (1 + sp->len == XFRM_MAX_DEPTH) goto drop; ... sp->xvec[sp->len++] = x; xfrm_input() can leave sp->len == XFRM_MAX_DEPTH, and the transport-mode receive path re-enters IPv6 input via xfrm_trans_reinject() with that secpath preserved. If the inner packet carries a destination-options HAO option or a type-2 routing header, xfrm6_input_addr() is called with sp->len == XFRM_MAX_DEPTH; the check (1 + 6 == 6) is false, so sp->xvec[sp->len++] writes one slot past the 6-element xvec[]. The write stays within the sec_path allocation (invisible to KASAN); UBSAN_BOUNDS flags it and panics under panic_on_warn. Use "sp->len >= XFRM_MAX_DEPTH", matching xfrm_input(). This also restores one chain level the old check rejected at sp->len == 5. UBSAN: array-index-out-of-bounds in net/ipv6/xfrm6_input.c:309:10 index 6 is out of range for type 'xfrm_state *[6]'

Affected packages & fixed versions

Affected products (as reported)

References

• https://git.kernel.org/stable/c/91fc387f63c00ddfb5221127a17bac97549a8343
• https://git.kernel.org/stable/c/68e8737fe8e72f085c608cff322b3d2de8340af1
• https://git.kernel.org/stable/c/8fe2c53fb81f5ad5be43af2ad09583f7c78b4b77
• https://git.kernel.org/stable/c/bdcda866c89f9a8b1acdabf02d26cde9fbe501d8
• https://git.kernel.org/stable/c/48996649222e95008cdb98cd58579e3fc8e5ee06
• https://git.kernel.org/stable/c/0f679e0523ddfff3fb554336ceb874b0e51e9cd3
• https://git.kernel.org/stable/c/5f35a29a5eed3d80befd32050843ac88dea3d61a
• https://git.kernel.org/stable/c/5d9e3bf34fec9a5d237e4b7cef4a707bc2e091bc