[PATCH] jfs: xattr: fix buffer overflow for invalid xattr

[PATCH] jfs: xattr: fix buffer overflow for invalid xattr

[Greg Kroah-Hartman]

When an xattr size is not what is expected, it is printed out to the
kernel log in hex format as a form of debugging.  But when that xattr
size is bigger than the expected size, printing it out can cause an
access off the end of the buffer.

Fix this all up by properly restricting the size of the debug hex dump
in the kernel log.

Reported-by: syzbot+9dfe490c8176301c1d06@syzkaller.appspotmail.com
Cc: Dave Kleikamp <shaggy@kernel.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
---
 fs/jfs/xattr.c | 4 +++-
 1 file changed, 3 insertions(+), 1 deletion(-)

diff --git a/fs/jfs/xattr.c b/fs/jfs/xattr.c
index 0fb7afac298e..9987055293b3 100644
--- a/fs/jfs/xattr.c
+++ b/fs/jfs/xattr.c
@@ -557,9 +557,11 @@ 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);
+
 		printk(KERN_ERR "ea_get: invalid extended attribute\n");
 		print_hex_dump(KERN_ERR, "", DUMP_PREFIX_ADDRESS, 16, 1,
-				     ea_buf->xattr, ea_size, 1);
+				     ea_buf->xattr, size, 1);
 		ea_release(inode, ea_buf);
 		rc = -EIO;
 		goto clean_up;
-- 
2.45.0