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btrfs: avoid null pointer dereference on fs_info when calling btrfs_crit

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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: efe120a067 ("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>
Signed-off-by: David Sterba <dsterba@suse.com>
This commit is contained in:
Colin Ian King 2017-09-11 16:15:28 +01:00 committed by David Sterba
parent fa0d0888bd
commit 3993b112da
1 changed files with 2 additions and 2 deletions
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4
fs/btrfs/super.c
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@ -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);
}