Linux kernel net/tls use-after-free via double cleanup when -EBUSY
CVE-2026-31533 Published on April 23, 2026
net/tls: fix use-after-free in -EBUSY error path of tls_do_encryption
In the Linux kernel, the following vulnerability has been resolved:
net/tls: fix use-after-free in -EBUSY error path of tls_do_encryption
The -EBUSY handling in tls_do_encryption(), introduced by commit
859054147318 ("net: tls: handle backlogging of crypto requests"), has
a use-after-free due to double cleanup of encrypt_pending and the
scatterlist entry.
When crypto_aead_encrypt() returns -EBUSY, the request is enqueued to
the cryptd backlog and the async callback tls_encrypt_done() will be
invoked upon completion. That callback unconditionally restores the
scatterlist entry (sge->offset, sge->length) and decrements
ctx->encrypt_pending. However, if tls_encrypt_async_wait() returns an
error, the synchronous error path in tls_do_encryption() performs the
same cleanup again, double-decrementing encrypt_pending and
double-restoring the scatterlist.
The double-decrement corrupts the encrypt_pending sentinel (initialized
to 1), making tls_encrypt_async_wait() permanently skip the wait for
pending async callbacks. A subsequent sendmsg can then free the
tls_rec via bpf_exec_tx_verdict() while a cryptd callback is still
pending, resulting in a use-after-free when the callback fires on the
freed record.
Fix this by skipping the synchronous cleanup when the -EBUSY async
wait returns an error, since the callback has already handled
encrypt_pending and sge restoration.
Products Associated with CVE-2026-31533
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Affected Versions
Linux:- Version 3ade391adc584f17b5570fd205de3ad029090368 and below 414fc5e5a5aff776c150f1b86770e0a25a35df3a is affected.
- Version cd1bbca03f3c1d845ce274c0d0a66de8e5929f72 and below 02f3ecadb23558bbe068e6504118f1b712d4ece0 is affected.
- Version 13eca403876bbea3716e82cdfe6f1e6febb38754 and below 0e43e0a3c94044acc74b8e0927c27972eb5a59e8 is affected.
- Version 8590541473188741055d27b955db0777569438e3 and below aa9facde6c5005205874c37db3fd25799d741baf is affected.
- Version 8590541473188741055d27b955db0777569438e3 and below 5d70eb25b41e9b010828cd12818b06a0c3b04412 is affected.
- Version 8590541473188741055d27b955db0777569438e3 and below 2694d408b0e595024e0fc1d64ff9db0358580f74 is affected.
- Version 8590541473188741055d27b955db0777569438e3 and below a9b8b18364fffce4c451e6f6fd218fa4ab646705 is affected.
- Version ab6397f072e5097f267abf5cb08a8004e6b17694 is affected.
- Version 6.8 is affected.
- Before 6.8 is unaffected.
- Version 5.15.203, <= 5.15.* is unaffected.
- Version 6.1.169, <= 6.1.* is unaffected.
- Version 6.6.135, <= 6.6.* is unaffected.
- Version 6.12.82, <= 6.12.* is unaffected.
- Version 6.18.23, <= 6.18.* is unaffected.
- Version 6.19.13, <= 6.19.* is unaffected.
- Version 7.0, <= * is unaffected.