From 0ef08ec1c2850a4b748e7685f018eadabcf23f57 Mon Sep 17 00:00:00 2001 From: Colin Ian King Date: Mon, 11 Sep 2017 16:15:28 +0100 Subject: [PATCH] btrfs: avoid null pointer dereference on fs_info when calling btrfs_crit commit 3993b112dac968612b0b213ed59cb30f50b0015b upstream. 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 Reviewed-by: David Sterba Signed-off-by: David Sterba [bwh: Backported to 3.16: adjust context] Signed-off-by: Ben Hutchings --- 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 3cec2fb4fdc1..72068ce50d76 100644 --- a/fs/btrfs/super.c +++ b/fs/btrfs/super.c @@ -185,7 +185,6 @@ static const char * const logtypes[] = { void btrfs_printk(const struct btrfs_fs_info *fs_info, const char *fmt, ...) { - struct super_block *sb = fs_info->sb; char lvl[4]; struct va_format vaf; va_list args; @@ -207,7 +206,8 @@ void btrfs_printk(const struct btrfs_fs_info *fs_info, const char *fmt, ...) vaf.fmt = fmt; vaf.va = &args; - 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 : "", &vaf); va_end(args); }