diff options
| author | Tristan Madani | 2026-04-17 19:54:57 +0000 |
|---|---|---|
| committer | Greg Kroah-Hartman | 2026-04-27 07:30:18 -0600 |
| commit | ef7902be3f215b6bf7babe4dc9dd9a7d57dad7a7 (patch) | |
| tree | f4711bb8c63a04486c7d07939a3f18d5de33477f /fs | |
| parent | 922d48fe8c19f388ffa2f709f33acaae4e408de2 (diff) | |
ksmbd: use check_add_overflow() to prevent u16 DACL size overflow
commit 299f962c0b02d048fb45d248b4da493d03f3175d upstream.
set_posix_acl_entries_dacl() and set_ntacl_dacl() accumulate ACE sizes
in u16 variables. When a file has many POSIX ACL entries, the
accumulated size can wrap past 65535, causing the pointer arithmetic
(char *)pndace + *size to land within already-written ACEs. Subsequent
writes then overwrite earlier entries, and pndacl->size gets a
truncated value.
Use check_add_overflow() at each accumulation point to detect the
wrap before it corrupts the buffer, consistent with existing
check_mul_overflow() usage elsewhere in smbacl.c.
Cc: stable@vger.kernel.org
Fixes: e2f34481b24d ("cifsd: add server-side procedures for SMB3")
Signed-off-by: Tristan Madani <tristan@talencesecurity.com>
Acked-by: Namjae Jeon <linkinjeon@kernel.org>
Signed-off-by: Steve French <stfrench@microsoft.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Diffstat (limited to 'fs')
| -rw-r--r-- | fs/smb/server/smbacl.c | 16 |
1 files changed, 12 insertions, 4 deletions
diff --git a/fs/smb/server/smbacl.c b/fs/smb/server/smbacl.c index a1de89cc09be..4bbc2c27e680 100644 --- a/fs/smb/server/smbacl.c +++ b/fs/smb/server/smbacl.c @@ -596,6 +596,7 @@ static void set_posix_acl_entries_dacl(struct mnt_idmap *idmap, struct smb_sid *sid; struct smb_ace *ntace; int i, j; + u16 ace_sz; if (!fattr->cf_acls) goto posix_default_acl; @@ -640,8 +641,10 @@ static void set_posix_acl_entries_dacl(struct mnt_idmap *idmap, flags = 0x03; ntace = (struct smb_ace *)((char *)pndace + *size); - *size += fill_ace_for_sid(ntace, sid, ACCESS_ALLOWED, flags, + ace_sz = fill_ace_for_sid(ntace, sid, ACCESS_ALLOWED, flags, pace->e_perm, 0777); + if (check_add_overflow(*size, ace_sz, size)) + break; (*num_aces)++; if (pace->e_tag == ACL_USER) ntace->access_req |= @@ -650,8 +653,10 @@ static void set_posix_acl_entries_dacl(struct mnt_idmap *idmap, if (S_ISDIR(fattr->cf_mode) && (pace->e_tag == ACL_USER || pace->e_tag == ACL_GROUP)) { ntace = (struct smb_ace *)((char *)pndace + *size); - *size += fill_ace_for_sid(ntace, sid, ACCESS_ALLOWED, + ace_sz = fill_ace_for_sid(ntace, sid, ACCESS_ALLOWED, 0x03, pace->e_perm, 0777); + if (check_add_overflow(*size, ace_sz, size)) + break; (*num_aces)++; if (pace->e_tag == ACL_USER) ntace->access_req |= @@ -691,8 +696,10 @@ posix_default_acl: } ntace = (struct smb_ace *)((char *)pndace + *size); - *size += fill_ace_for_sid(ntace, sid, ACCESS_ALLOWED, 0x0b, + ace_sz = fill_ace_for_sid(ntace, sid, ACCESS_ALLOWED, 0x0b, pace->e_perm, 0777); + if (check_add_overflow(*size, ace_sz, size)) + break; (*num_aces)++; if (pace->e_tag == ACL_USER) ntace->access_req |= @@ -728,7 +735,8 @@ static void set_ntacl_dacl(struct mnt_idmap *idmap, break; memcpy((char *)pndace + size, ntace, nt_ace_size); - size += nt_ace_size; + if (check_add_overflow(size, nt_ace_size, &size)) + break; aces_size -= nt_ace_size; ntace = (struct smb_ace *)((char *)ntace + nt_ace_size); num_aces++; |