6.12-stable review patch. If anyone has any objections, please let me know.
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From: Norbert Szetei norbert@doyensec.com
commit beff0bc9d69bc8e733f9bca28e2d3df5b3e10e42 upstream.
The dacloffset field was originally typed as int and used in an unchecked addition, which could overflow and bypass the existing bounds check in both smb_check_perm_dacl() and smb_inherit_dacl().
This could result in out-of-bounds memory access and a kernel crash when dereferencing the DACL pointer.
This patch converts dacloffset to unsigned int and uses check_add_overflow() to validate access to the DACL.
Cc: stable@vger.kernel.org Signed-off-by: Norbert Szetei norbert@doyensec.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 --- fs/smb/server/smbacl.c | 16 ++++++++++++---- 1 file changed, 12 insertions(+), 4 deletions(-)
--- a/fs/smb/server/smbacl.c +++ b/fs/smb/server/smbacl.c @@ -1026,7 +1026,9 @@ int smb_inherit_dacl(struct ksmbd_conn * struct dentry *parent = path->dentry->d_parent; struct mnt_idmap *idmap = mnt_idmap(path->mnt); int inherited_flags = 0, flags = 0, i, nt_size = 0, pdacl_size; - int rc = 0, dacloffset, pntsd_type, pntsd_size, acl_len, aces_size; + int rc = 0, pntsd_type, pntsd_size, acl_len, aces_size; + unsigned int dacloffset; + size_t dacl_struct_end; u16 num_aces, ace_cnt = 0; char *aces_base; bool is_dir = S_ISDIR(d_inode(path->dentry)->i_mode); @@ -1035,8 +1037,11 @@ int smb_inherit_dacl(struct ksmbd_conn * parent, &parent_pntsd); if (pntsd_size <= 0) return -ENOENT; + dacloffset = le32_to_cpu(parent_pntsd->dacloffset); - if (!dacloffset || (dacloffset + sizeof(struct smb_acl) > pntsd_size)) { + if (!dacloffset || + check_add_overflow(dacloffset, sizeof(struct smb_acl), &dacl_struct_end) || + dacl_struct_end > (size_t)pntsd_size) { rc = -EINVAL; goto free_parent_pntsd; } @@ -1239,7 +1244,9 @@ int smb_check_perm_dacl(struct ksmbd_con struct smb_ntsd *pntsd = NULL; struct smb_acl *pdacl; struct posix_acl *posix_acls; - int rc = 0, pntsd_size, acl_size, aces_size, pdacl_size, dacl_offset; + int rc = 0, pntsd_size, acl_size, aces_size, pdacl_size; + unsigned int dacl_offset; + size_t dacl_struct_end; struct smb_sid sid; int granted = le32_to_cpu(*pdaccess & ~FILE_MAXIMAL_ACCESS_LE); struct smb_ace *ace; @@ -1258,7 +1265,8 @@ int smb_check_perm_dacl(struct ksmbd_con
dacl_offset = le32_to_cpu(pntsd->dacloffset); if (!dacl_offset || - (dacl_offset + sizeof(struct smb_acl) > pntsd_size)) + check_add_overflow(dacl_offset, sizeof(struct smb_acl), &dacl_struct_end) || + dacl_struct_end > (size_t)pntsd_size) goto err_out;
pdacl = (struct smb_acl *)((char *)pntsd + le32_to_cpu(pntsd->dacloffset));