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fs/befs/linuxvfs.c: check superblock before dump operation 

befs_dump_super_block was called between befs_load_sb and befs_check_sb.
It has been reported to crash (5/900) with null block testing.

This patch loads, checks and only dump superblock if it's a valid one
then brelse bh.

(befs_dump_super_block uses disk_sb (bh->b_data) so it seems we need to
call it before brelse(bh) but I don't know why befs_check_sb was called
after brelse.  Another thing I don't understand is why this problem
appears now).

Signed-off-by: Fabian Frederick <fabf@skynet.be>
Reported-by: Fengguang Wu <fengguang.wu@intel.com>
Cc: Joe Perches <joe@perches.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
This commit is contained in:
Fabian Frederick 2014-08-08 14:20:31 -07:00 committed by Linus Torvalds
parent 6d6747f853
commit 8e19189ef8
1 changed files with 2 additions and 4 deletions
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6
fs/befs/linuxvfs.c
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@ -832,16 +832,14 @@ befs_fill_super(struct super_block *sb, void *data, int silent)
(befs_super_block *) ((void *) bh->b_data + x86_sb_off);
}
if (befs_load_sb(sb, disk_sb) != BEFS_OK)
if ((befs_load_sb(sb, disk_sb) != BEFS_OK) ||
(befs_check_sb(sb) != BEFS_OK))
goto unacquire_bh;
befs_dump_super_block(sb, disk_sb);
brelse(bh);
if (befs_check_sb(sb) != BEFS_OK)
goto unacquire_priv_sbp;
if( befs_sb->num_blocks > ~((sector_t)0) ) {
befs_error(sb, "blocks count: %llu "
"is larger than the host can use",