smb: client: fix in-place encryption corruption in SMB2_write()

Summary

In the Linux kernel, the following vulnerability has been resolved: smb: client: fix in-place encryption corruption in SMB2_write() SMB2_write() places write payload in iov[1..n] as part of rq_iov. smb3_init_transform_rq() pointer-shares rq_iov, so crypt_message() encrypts iov[1] in-place, replacing the original plaintext with ciphertext. On a replayable error, the retry sends the same iov[1] which now contains ciphertext instead of the original data, resulting in corruption. The corruption is most likely to be observed when connections are unstable, as reconnects trigger write retries that re-send the already-encrypted data. This affects SFU mknod, MF symlinks, etc. On kernels before 6.10 (prior to the netfs conversion), sync writes also used this path and were similarly affected. The async write path wasn't unaffected as it uses rq_iter which gets deep-copied. Fix by moving the write payload into rq_iter via iov_iter_kvec(), so smb3_init_transform_rq() deep-copies it before encryption.

Timeline

1. May 8, 2026, 2:21 PM UTCCVE published
2. Oct 16, 2026, 3:16 PM UTCCISA SSVC assessment

   Exploitation: none · Automatable: no · Technical impact: partial

3. Oct 19, 2026, 7:16 PM UTCRecord last updated

Affected versions

• Linux Linux

  From 026e93dc0a3eefb0be060bcb9ecd8d7a7fd5c398 · fixed in 438e77435aee2894d5edf90be5c87004a57f6258; From 026e93dc0a3eefb0be060bcb9ecd8d7a7fd5c398 · fixed in 52327268224fb9ccc7ecfbbdfdfff54b6e93c518; From 026e93dc0a3eefb0be060bcb9ecd8d7a7fd5c398 · fixed in 92e64f1852f455f57d0850989e57c30d7fac7d95; From 026e93dc0a3eefb0be060bcb9ecd8d7a7fd5c398 · fixed in aea5e37388a080361110ab5790f57ae0af383650; From 026e93dc0a3eefb0be060bcb9ecd8d7a7fd5c398 · fixed in d78840a6a38d312dc1a51a65317bb67e46f0b929

• Linux Linux

  4.11

• KernelLinux

  From 4.11.0 · fixed in 6.6.130; From 6.7.0 · fixed in 6.12.78; From 6.13.0 · fixed in 6.18.19; From 6.19.0 · fixed in 6.19.9

References 5