From: Bjoern Doebel Date: Thu, 30 Apr 2026 08:57:17 +0000 (+0000) Subject: smb: client: use kzalloc to zero-initialize security descriptor buffer X-Git-Tag: v7.1-rc3~20^2~5 X-Git-Url: http://git.ipfire.org/cgi-bin/gitweb.cgi?a=commitdiff_plain;h=5e489c6c47a2ac15edbaca153b9348e42c1eacab;p=thirdparty%2Fkernel%2Flinux.git smb: client: use kzalloc to zero-initialize security descriptor buffer Commit 62e7dd0a39c2d ("smb: common: change the data type of num_aces to le16") split struct smb_acl's __le32 num_aces field into __le16 num_aces and __le16 reserved. The reserved field corresponds to Sbz2 in the MS-DTYP ACL wire format, which must be zero [1]. When building an ACL descriptor in build_sec_desc(), we are using a kmalloc()'ed descriptor buffer and writing the fields explicitly using le16() writes now. This never writes to the 2 byte reserved field, leaving it as uninitialized heap data. When the reserved field happens to contain non-zero slab garbage, Samba rejects the security descriptor with "ndr_pull_security_descriptor failed: Range Error", causing chmod to fail with EINVAL. Change kmalloc() to kzalloc() to ensure the entire buffer is zero-initialized. Fixes: 62e7dd0a39c2d ("smb: common: change the data type of num_aces to le16") Cc: stable@vger.kernel.org Signed-off-by: Bjoern Doebel Assisted-by: Kiro:claude-opus-4.6 [1] https://learn.microsoft.com/en-us/openspecs/windows_protocols/ms-dtyp/20233ed8-a6c6-4097-aafa-dd545ed24428 Signed-off-by: Steve French --- diff --git a/fs/smb/client/cifsacl.c b/fs/smb/client/cifsacl.c index ec5d47779304..a2750f1e3d90 100644 --- a/fs/smb/client/cifsacl.c +++ b/fs/smb/client/cifsacl.c @@ -1732,7 +1732,7 @@ id_mode_to_cifs_acl(struct inode *inode, const char *path, __u64 *pnmode, * descriptor parameters, and security descriptor itself */ nsecdesclen = max_t(u32, nsecdesclen, DEFAULT_SEC_DESC_LEN); - pnntsd = kmalloc(nsecdesclen, GFP_KERNEL); + pnntsd = kzalloc(nsecdesclen, GFP_KERNEL); if (!pnntsd) { kfree(pntsd); cifs_put_tlink(tlink);