* [PATCH] btrfs: avoid null pointer dereference on fs_info when calling btrfs_crit
@ 2017-09-11 15:15 Colin King
2017-09-12 11:26 ` David Sterba
0 siblings, 1 reply; 2+ messages in thread
From: Colin King @ 2017-09-11 15:15 UTC (permalink / raw)
To: Chris Mason, Josef Bacik, David Sterba, linux-btrfs
Cc: kernel-janitors, linux-kernel
From: Colin Ian King <colin.king@canonical.com>
There are checks on fs_info in __btrfs_panic to avoid dereferencing a
null fs_info, however, there is a call to btrfs_crit that may also
dereference a null fs_info. Fix this by adding a check to see if fs_info
is null and only print the s_id if fs_info is non-null.
Detected by CoverityScan CID#401973 ("Dereference after null check")
Fixes: efe120a067c8 ("Btrfs: convert printk to btrfs_ and fix BTRFS prefix")
Signed-off-by: Colin Ian King <colin.king@canonical.com>
---
fs/btrfs/super.c | 4 ++--
1 file changed, 2 insertions(+), 2 deletions(-)
diff --git a/fs/btrfs/super.c b/fs/btrfs/super.c
index e56a93f3113e..c669241f936e 100644
--- a/fs/btrfs/super.c
+++ b/fs/btrfs/super.c
@@ -202,7 +202,6 @@ static struct ratelimit_state printk_limits[] = {
void btrfs_printk(const struct btrfs_fs_info *fs_info, const char *fmt, ...)
{
- struct super_block *sb = fs_info->sb;
char lvl[PRINTK_MAX_SINGLE_HEADER_LEN + 1] = "\0";
struct va_format vaf;
va_list args;
@@ -228,7 +227,8 @@ void btrfs_printk(const struct btrfs_fs_info *fs_info, const char *fmt, ...)
vaf.va = &args;
if (__ratelimit(ratelimit))
- printk("%sBTRFS %s (device %s): %pV\n", lvl, type, sb->s_id, &vaf);
+ printk("%sBTRFS %s (device %s): %pV\n", lvl, type,
+ fs_info ? fs_info->sb->s_id : "<unknown>", &vaf);
va_end(args);
}
--
2.14.1
^ permalink raw reply related [flat|nested] 2+ messages in thread
* Re: [PATCH] btrfs: avoid null pointer dereference on fs_info when calling btrfs_crit
2017-09-11 15:15 [PATCH] btrfs: avoid null pointer dereference on fs_info when calling btrfs_crit Colin King
@ 2017-09-12 11:26 ` David Sterba
0 siblings, 0 replies; 2+ messages in thread
From: David Sterba @ 2017-09-12 11:26 UTC (permalink / raw)
To: Colin King
Cc: Chris Mason, Josef Bacik, David Sterba, linux-btrfs,
kernel-janitors, linux-kernel
On Mon, Sep 11, 2017 at 04:15:28PM +0100, Colin King wrote:
> From: Colin Ian King <colin.king@canonical.com>
>
> There are checks on fs_info in __btrfs_panic to avoid dereferencing a
> null fs_info, however, there is a call to btrfs_crit that may also
> dereference a null fs_info. Fix this by adding a check to see if fs_info
> is null and only print the s_id if fs_info is non-null.
>
> Detected by CoverityScan CID#401973 ("Dereference after null check")
>
> Fixes: efe120a067c8 ("Btrfs: convert printk to btrfs_ and fix BTRFS prefix")
> Signed-off-by: Colin Ian King <colin.king@canonical.com>
Reviewed-by: David Sterba <dsterba@suse.com>
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