jfs: xattr: fix buffer overflow for invalid xattr

commit 7c55b78818cfb732680c4a72ab270cc2d2ee3d0f upstream.

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>
Link: https://lore.kernel.org/r/2024051433-slider-cloning-98f9@gregkh
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

diff --git a/fs/jfs/xattr.c b/fs/jfs/xattr.c
index db41e7803163ec00f866ec9ce5f61d1292851f87..7ae54f78a5b0b27b3a98f33828206311a30354fe 100644 (file)
--- 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;