Linux kernel TLS sg_chain off-by-one in sk_msg ring
CVE-2026-64047 Published on July 19, 2026
net: tls: fix off-by-one in sg_chain entry count for wrapped sk_msg ring
In the Linux kernel, the following vulnerability has been resolved:
net: tls: fix off-by-one in sg_chain entry count for wrapped sk_msg ring
When an sk_msg scatterlist ring wraps (sg.end < sg.start),
tls_push_record() chains the tail portion of the ring to the head
using sg_chain(). An extra entry in the sg array is reserved for
this:
struct sk_msg_sg {
[...]
/* The extra two elements:
* 1) used for chaining the front and sections when the list becomes
* partitioned (e.g. end < start). The crypto APIs require the
* chaining;
* 2) to chain tailer SG entries after the message.
*/
struct scatterlist data[MAX_MSG_FRAGS + 2];
The current code uses MAX_SKB_FRAGS + 1 as the ring size:
sg_chain(&msg_pl->sg.data[msg_pl->sg.start],
MAX_SKB_FRAGS - msg_pl->sg.start + 1,
msg_pl->sg.data);
This places the chain pointer at
sg_chain(data[start], (MAX_SKB_FRAGS - msg_start + 1) .. =
&data[start] + (MAX_SKB_FRAGS - msg_start + 1) - 1 =
data[start + (MAX_SKB_FRAGS - start + 1) - 1] =
data[MAX_SKB_FRAGS]
instead of the true last entry. This is likely due to a "race" of
the commit under Fixes landing close to
commit 031097d9e079 ("bpf: sk_msg, zap ingress queue on psock down")
Convert to ARRAY_SIZE and drop the data[start] / - start (as suggested
by Sabrina).
Products Associated with CVE-2026-64047
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Affected Versions
Linux:- Version 9aaaa56845a06aeabdd597cbe19492dc01f281ec and below 73963a375885d5ccb7def39fd0b4f542e0f343dd is affected.
- Version 9aaaa56845a06aeabdd597cbe19492dc01f281ec and below 47110c3a9ac247b688657337f5981efcfcb240dc is affected.
- Version 9aaaa56845a06aeabdd597cbe19492dc01f281ec and below 84158c2997159df4a0d70cd9c46774512d32a522 is affected.
- Version 9aaaa56845a06aeabdd597cbe19492dc01f281ec and below 131ef12057d92b77b636321b7849c69222405a97 is affected.
- Version 9aaaa56845a06aeabdd597cbe19492dc01f281ec and below 66339b71f105e6f83e0da3b9583d95077534fe1d is affected.
- Version 9aaaa56845a06aeabdd597cbe19492dc01f281ec and below eca989eab4b2599dcb02f72140a7c08f08838520 is affected.
- Version 9aaaa56845a06aeabdd597cbe19492dc01f281ec and below 2fb0dc7e0099686c4e9d2732745d8a31b18c3628 is affected.
- Version 9aaaa56845a06aeabdd597cbe19492dc01f281ec and below 285943c6e7ca309bbea84b253745154241d9788a is affected.
- Version d529d6c9f7e3aaeac13c4948f79799ccb825f29d is affected.
- Version 5.4.14 and below 5.5 is affected.
- Version 5.5 is affected.
- Before 5.5 is unaffected.
- Version 5.10.258, <= 5.10.* is unaffected.
- Version 5.15.209, <= 5.15.* is unaffected.
- Version 6.1.175, <= 6.1.* is unaffected.
- Version 6.6.142, <= 6.6.* is unaffected.
- Version 6.12.92, <= 6.12.* is unaffected.
- Version 6.18.34, <= 6.18.* is unaffected.
- Version 7.0.11, <= 7.0.* is unaffected.
- Version 7.1, <= * is unaffected.