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GET /api/patches/2224103/?format=api
{ "id": 2224103, "url": "http://patchwork.ozlabs.org/api/patches/2224103/?format=api", "web_url": "http://patchwork.ozlabs.org/project/linux-cifs-client/patch/20260416193325.2950619-1-michael.bommarito@gmail.com/", "project": { "id": 12, "url": "http://patchwork.ozlabs.org/api/projects/12/?format=api", "name": "Linux CIFS Client", "link_name": "linux-cifs-client", "list_id": "linux-cifs.vger.kernel.org", "list_email": "linux-cifs@vger.kernel.org", "web_url": "", "scm_url": "", "webscm_url": "", "list_archive_url": "", "list_archive_url_format": "", "commit_url_format": "" }, "msgid": "<20260416193325.2950619-1-michael.bommarito@gmail.com>", "list_archive_url": null, "date": "2026-04-16T19:33:25", "name": "smb: client: fix OOB reads from server-supplied dacloffset in cifsacl", "commit_ref": null, "pull_url": null, "state": "new", "archived": false, "hash": "8ca061df186837c091fbe39636b075c0f6be7f6b", "submitter": { "id": 93078, "url": "http://patchwork.ozlabs.org/api/people/93078/?format=api", "name": "Michael Bommarito", "email": "michael.bommarito@gmail.com" }, "delegate": null, "mbox": "http://patchwork.ozlabs.org/project/linux-cifs-client/patch/20260416193325.2950619-1-michael.bommarito@gmail.com/mbox/", "series": [ { "id": 500198, "url": "http://patchwork.ozlabs.org/api/series/500198/?format=api", "web_url": "http://patchwork.ozlabs.org/project/linux-cifs-client/list/?series=500198", "date": "2026-04-16T19:33:25", "name": "smb: client: fix OOB reads from server-supplied dacloffset in cifsacl", "version": 1, "mbox": "http://patchwork.ozlabs.org/series/500198/mbox/" } ], "comments": "http://patchwork.ozlabs.org/api/patches/2224103/comments/", "check": "pending", "checks": "http://patchwork.ozlabs.org/api/patches/2224103/checks/", "tags": {}, "related": [], "headers": { "Return-Path": "\n <linux-cifs+bounces-10871-incoming=patchwork.ozlabs.org@vger.kernel.org>", "X-Original-To": [ "incoming@patchwork.ozlabs.org", "linux-cifs@vger.kernel.org" ], "Delivered-To": "patchwork-incoming@legolas.ozlabs.org", "Authentication-Results": [ "legolas.ozlabs.org;\n\tdkim=pass (2048-bit key;\n unprotected) header.d=gmail.com header.i=@gmail.com header.a=rsa-sha256\n header.s=20251104 header.b=IluCM8BE;\n\tdkim-atps=neutral", "legolas.ozlabs.org;\n spf=pass (sender SPF authorized) smtp.mailfrom=vger.kernel.org\n (client-ip=2600:3c04:e001:36c::12fc:5321; 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Sorry for the piecemeal sends as I work through triaging\nall of my personal \"clanker\" pipeline results.\n\nHere is another malicious server issue, this time in two call sites\nin fs/smb/client/cifsacl.c. We compute a DACL pointer from a\nserver-supplied dacloffset and then read struct smb_acl fields \n(dacl_ptr->size, dacl_ptr->num_aces) without first checking that the\n8-byte struct header fits within the security descriptor buffer.\n\n1. build_sec_desc() -- chmod path:\n\n dacl_ptr = (struct smb_acl *)((char *)pntsd + dacloffset);\n if (end_of_acl < (char *)dacl_ptr + le16_to_cpu(dacl_ptr->size))\n\n2. id_mode_to_cifs_acl() -- chown path:\n\n dacl_ptr = (struct smb_acl *)((char *)pntsd + dacloffset);\n ...\n le16_to_cpu(dacl_ptr->num_aces) * sizeof(struct smb_ace);\n le16_to_cpu(dacl_ptr->size);\n\nIn both cases, if dacloffset places dacl_ptr at or past end_of_acl,\nthe le16_to_cpu() dereferences are OOB heap reads.\n\nReproduced under UML + KASAN by constructing a 20-byte smb_ntsd\n(sizeof(struct smb_ntsd)) with dacloffset = 20, placing dacl_ptr at\nthe exact end of the allocation. The le16_to_cpu(dacl_ptr->size)\nread triggers:\n\n BUG: KASAN: slab-out-of-bounds in kcifs2_test_build_sec_desc_old\n Read of size 2 at addr ... by task mount.nfs4/220\n\nConfirmed -EINVAL without splat after patch applied.\n\nparse_dacl() already handles this correctly with a two-step check that\nvalidates the struct header fits before reading the size field:\n\n if (end_of_acl < (char *)pdacl + sizeof(struct smb_acl) ||\n end_of_acl < (char *)pdacl + le16_to_cpu(pdacl->size))\n\nApply the same pattern to both sites. This is the client-side\ncounterpart of commit beff0bc9d69b (\"ksmbd: fix overflow in dacloffset\nbounds check\") which fixed the identical class of issue on the server\nside.\n\nFixes: bc3e9dd9d104 (\"cifs: Change SIDs in ACEs while transferring file ownership.\")\nCc: stable@vger.kernel.org\nAssisted-by: Claude:claude-opus-4-6\nSigned-off-by: Michael Bommarito <michael.bommarito@gmail.com>\n---\n fs/smb/client/cifsacl.c | 11 ++++++++++-\n 1 file changed, 10 insertions(+), 1 deletion(-)", "diff": "diff --git a/fs/smb/client/cifsacl.c b/fs/smb/client/cifsacl.c\nindex c920039d733c..115990467dfa 100644\n--- a/fs/smb/client/cifsacl.c\n+++ b/fs/smb/client/cifsacl.c\n@@ -1293,7 +1293,8 @@ static int build_sec_desc(struct smb_ntsd *pntsd, struct smb_ntsd *pnntsd,\n \tdacloffset = le32_to_cpu(pntsd->dacloffset);\n \tif (dacloffset) {\n \t\tdacl_ptr = (struct smb_acl *)((char *)pntsd + dacloffset);\n-\t\tif (end_of_acl < (char *)dacl_ptr + le16_to_cpu(dacl_ptr->size)) {\n+\t\tif (end_of_acl < (char *)dacl_ptr + sizeof(struct smb_acl) ||\n+\t\t end_of_acl < (char *)dacl_ptr + le16_to_cpu(dacl_ptr->size)) {\n \t\t\tcifs_dbg(VFS, \"Server returned illegal ACL size\\n\");\n \t\t\treturn -EINVAL;\n \t\t}\n@@ -1662,6 +1663,14 @@ id_mode_to_cifs_acl(struct inode *inode, const char *path, __u64 *pnmode,\n \t\tdacloffset = le32_to_cpu(pntsd->dacloffset);\n \t\tif (dacloffset) {\n \t\t\tdacl_ptr = (struct smb_acl *)((char *)pntsd + dacloffset);\n+\t\t\tif ((char *)pntsd + secdesclen <\n+\t\t\t (char *)dacl_ptr + sizeof(struct smb_acl)) {\n+\t\t\t\tcifs_dbg(VFS, \"Server returned illegal dacloffset\\n\");\n+\t\t\t\trc = -EINVAL;\n+\t\t\t\tkfree(pntsd);\n+\t\t\t\tcifs_put_tlink(tlink);\n+\t\t\t\treturn rc;\n+\t\t\t}\n \t\t\tif (mode_from_sid)\n \t\t\t\tnsecdesclen +=\n \t\t\t\t\tle16_to_cpu(dacl_ptr->num_aces) * sizeof(struct smb_ace);\n", "prefixes": [] }