This is a note to let you know that I've just added the patch titled cifs: potential buffer overflow in handling symlinks to the 4.19-stable tree which can be found at: http://www.kernel.org/git/?p=linux/kernel/git/stable/stable-queue.git;a=summary The filename of the patch is: cifs-potential-buffer-overflow-in-handling-symlinks.patch and it can be found in the queue-4.19 subdirectory. If you, or anyone else, feels it should not be added to the stable tree, please let <stable@xxxxxxxxxxxxxxx> know about it. commit be14ba52f99235c047331fc5dbd9a51a340c5d2c Author: Harshit Mogalapalli <harshit.m.mogalapalli@xxxxxxxxxx> Date: Wed Apr 13 04:42:51 2022 -0700 cifs: potential buffer overflow in handling symlinks [ Upstream commit 64c4a37ac04eeb43c42d272f6e6c8c12bfcf4304 ] Smatch printed a warning: arch/x86/crypto/poly1305_glue.c:198 poly1305_update_arch() error: __memcpy() 'dctx->buf' too small (16 vs u32max) It's caused because Smatch marks 'link_len' as untrusted since it comes from sscanf(). Add a check to ensure that 'link_len' is not larger than the size of the 'link_str' buffer. Fixes: c69c1b6eaea1 ("cifs: implement CIFSParseMFSymlink()") Signed-off-by: Harshit Mogalapalli <harshit.m.mogalapalli@xxxxxxxxxx> Reviewed-by: Ronnie Sahlberg <lsahlber@xxxxxxxxxx> Signed-off-by: Steve French <stfrench@xxxxxxxxxxxxx> Signed-off-by: Sasha Levin <sashal@xxxxxxxxxx> diff --git a/fs/cifs/link.c b/fs/cifs/link.c index 2148b0f60e5e..5b1c33d9283a 100644 --- a/fs/cifs/link.c +++ b/fs/cifs/link.c @@ -97,6 +97,9 @@ parse_mf_symlink(const u8 *buf, unsigned int buf_len, unsigned int *_link_len, if (rc != 1) return -EINVAL; + if (link_len > CIFS_MF_SYMLINK_LINK_MAXLEN) + return -EINVAL; + rc = symlink_hash(link_len, link_str, md5_hash); if (rc) { cifs_dbg(FYI, "%s: MD5 hash failure: %d\n", __func__, rc);