jfs: xattr: check invalid xattr size more strictly

Commit 7c55b78 ("jfs: xattr: fix buffer overflow for invalid xattr")
also addresses this issue but it only fixes it for positive values, while
ea_size is an integer type and can take negative values, e.g. in case of
a corrupted filesystem. This still breaks validation and would overflow
because of implicit conversion from int to size_t in print_hex_dump().

Fix this issue by clamping the ea_size value instead.

Found by Linux Verification Center (linuxtesting.org) with Syzkaller.

Cc: [email protected]
Signed-off-by: Artem Sadovnikov <[email protected]>
Signed-off-by: Dave Kleikamp <[email protected]>

Author: Artem Sadovnikov

fs/jfs/xattr.c

@@ -559,7 +559,7 @@ static int ea_get(struct inode *inode, struct ea_buffer *ea_buf, int min_size)
 
       size_check:
 	if (EALIST_SIZE(ea_buf->xattr) != ea_size) {
-		int size = min_t(int, EALIST_SIZE(ea_buf->xattr), ea_size);
+		int size = clamp_t(int, ea_size, 0, EALIST_SIZE(ea_buf->xattr));
 
 		printk(KERN_ERR "ea_get: invalid extended attribute\n");
 		print_hex_dump(KERN_ERR, "", DUMP_PREFIX_ADDRESS, 16, 1,