diff mbox series

exfat: Fix pontential use after free in exfat_load_upcase_table()

Message ID 20200608141629.GA1912173@mwanda (mailing list archive)
State New, archived
Headers show
Series exfat: Fix pontential use after free in exfat_load_upcase_table() | expand

Commit Message

Dan Carpenter June 8, 2020, 2:16 p.m. UTC
This code calls brelse(bh) and then dereferences "bh" on the next line
resulting in a possible use after free.  The brelse() should just be
moved down a line.

Fixes: b676fdbcf4c8 ("exfat: standardize checksum calculation")
Signed-off-by: Dan Carpenter <dan.carpenter@oracle.com>
---
 fs/exfat/nls.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

Comments

Namjae Jeon June 9, 2020, 12:37 a.m. UTC | #1
> This code calls brelse(bh) and then dereferences "bh" on the next line resulting in a possible use
> after free.  The brelse() should just be moved down a line.
> 
> Fixes: b676fdbcf4c8 ("exfat: standardize checksum calculation")
> Signed-off-by: Dan Carpenter <dan.carpenter@oracle.com>
Applied. Thanks!
> ---
>  fs/exfat/nls.c | 2 +-
>  1 file changed, 1 insertion(+), 1 deletion(-)
> 
> diff --git a/fs/exfat/nls.c b/fs/exfat/nls.c index c1ec056954974..57b5a7a4d1f7a 100644
> --- a/fs/exfat/nls.c
> +++ b/fs/exfat/nls.c
> @@ -692,8 +692,8 @@ static int exfat_load_upcase_table(struct super_block *sb,
>  				index++;
>  			}
>  		}
> -		brelse(bh);
>  		chksum = exfat_calc_chksum32(bh->b_data, i, chksum, CS_DEFAULT);
> +		brelse(bh);
>  	}
> 
>  	if (index >= 0xFFFF && utbl_checksum == chksum)
> --
> 2.26.2
diff mbox series

Patch

diff --git a/fs/exfat/nls.c b/fs/exfat/nls.c
index c1ec056954974..57b5a7a4d1f7a 100644
--- a/fs/exfat/nls.c
+++ b/fs/exfat/nls.c
@@ -692,8 +692,8 @@  static int exfat_load_upcase_table(struct super_block *sb,
 				index++;
 			}
 		}
-		brelse(bh);
 		chksum = exfat_calc_chksum32(bh->b_data, i, chksum, CS_DEFAULT);
+		brelse(bh);
 	}
 
 	if (index >= 0xFFFF && utbl_checksum == chksum)