CVE-2026-90125

Description

In the Linux kernel, the following vulnerability has been resolved: smb: client: fix request buffer leak in smb2_new_read_req() smb2_new_read_req() allocates the request buffer with smb2_plain_req_init() but only publishes it to the caller with *buf = req at the very end of the function. Two error returns sit in between: rc = smb2_plain_req_init(SMB2_READ, io_parms->tcon, server, (void **) &req, total_len); if (rc) return rc; if (server == NULL) return -ECONNABORTED; [...] rdata->mr = smbd_register_mr(server->smbd_conn, &rdata->subreq.io_iter, true, need_invalidate); if (!rdata->mr) return -EAGAIN; On either of them the buffer is neither released nor handed back, so it is leaked. The caller cannot clean up after it: smb2_async_readv() does 'goto out' on a non-zero return, which skips the cifs_small_buf_release(buf) at async_readv_out, and buf has not been assigned at that point in any case. The write path has never had this problem. smb2_async_writev() registers the memory region inline and jumps to its release label instead of returning: wdata->mr = smbd_register_mr(...); if (!wdata->mr) { rc = -EAGAIN; goto async_writev_out; } Commit b7972092199f ("cifs: smbd: Retry on memory registration failure") changed both sides from -ENOBUFS to -EAGAIN in a single patch, which puts the two shapes next to each other. Only the -EAGAIN return is reachable in practice, because smb2_plain_req_init() calls smb2_reconnect() first and that already fails with -EIO when server is NULL, before anything is allocated. Both returns are given the same treatment here rather than leaving one of them correct only by accident. Because -EAGAIN is a replayable error, the failure also reaches the retry block at the end of smb2_async_readv(), which marks the subrequest NETFS_SREQ_NEED_RETRY, so a failing registration can be retried rather than ending the I/O, and every attempt that reaches it leaks another buffer. smb2_should_replay() short-circuits on tcon->retry, so on a hard mount the attempt count is not bounded by the retrans setting. Only the asynchronous read path is affected. The synchronous SMB2_read() caller passes rdata == NULL and the memory registration block is guarded on rdata. The memory registration failure path was pointed out by the Sashiko AI reviewer while it was reviewing an unrelated patch to smb2_async_readv().

Gravité et risque d'exploitation

CVE-2026-90125 obtient un score CVSS de 0.0/10, soit une gravité non évaluée. Selon le modèle EPSS, la probabilité qu'elle soit exploitée dans les 30 prochains jours est de 0.20 %, ce qui la place devant 9.3 % des CVE référencées.

Que faire ?

• Vérifiez si Linux (versions <73f6bdb0380486ab37fe12cd74de20abfaf5d3ae, <=6.12.*, <4.16, 0, 6.18.52, <12092ed28434bf41e08d41e3c5269eb6b337fc02, <deb6468f4164640e4dc875f008aa449cf55987a5, <=6.6.*, 6.6.157, bd3dcc6a22a9186ed78da51ce09e889803552189, <442c5f1358ced0d4e716778ac06f1e323a7e4f21, 7.2.6, <=6.18.*, <=7.2.*, 6.12.110, 4.16, <=*, <58066940076b90c16e821fd6f9767cd979cbdb5e, 7.3) est présent sur votre parc.
• Appliquez le correctif ou la version corrigée indiqués dans les références de l'éditeur.
• À défaut de correctif, limitez l'exposition (filtrage réseau, désactivation du composant).
• Automatisez la détection : les agents CVE Heimdall (gratuits, open source) corrèlent l'inventaire de vos serveurs avec la base CVE.

Références

• https://git.kernel.org/stable/c/58066940076b90c16e821fd6f9767cd979cbdb5e
• https://git.kernel.org/stable/c/12092ed28434bf41e08d41e3c5269eb6b337fc02
• https://git.kernel.org/stable/c/442c5f1358ced0d4e716778ac06f1e323a7e4f21
• https://git.kernel.org/stable/c/73f6bdb0380486ab37fe12cd74de20abfaf5d3ae
• https://git.kernel.org/stable/c/deb6468f4164640e4dc875f008aa449cf55987a5