From: Ryusuke Konishi Date: Sat, 17 Mar 2012 00:08:39 +0000 (-0700) Subject: nilfs2: fix NULL pointer dereference in nilfs_load_super_block() X-Git-Tag: v3.3~4^2 X-Git-Url: https://asedeno.scripts.mit.edu/gitweb/?a=commitdiff_plain;h=d7178c79d9b7c5518f9943188091a75fc6ce0675;p=linux.git nilfs2: fix NULL pointer dereference in nilfs_load_super_block() According to the report from Slicky Devil, nilfs caused kernel oops at nilfs_load_super_block function during mount after he shrank the partition without resizing the filesystem: BUG: unable to handle kernel NULL pointer dereference at 00000048 IP: [] nilfs_load_super_block+0x17e/0x280 [nilfs2] *pde = 00000000 Oops: 0000 [#1] PREEMPT SMP ... Call Trace: [] init_nilfs+0x4b/0x2e0 [nilfs2] [] nilfs_mount+0x447/0x5b0 [nilfs2] [] mount_fs+0x36/0x180 [] vfs_kern_mount+0x51/0xa0 [] do_kern_mount+0x3e/0xe0 [] do_mount+0x169/0x700 [] sys_mount+0x6b/0xa0 [] sysenter_do_call+0x12/0x28 Code: 53 18 8b 43 20 89 4b 18 8b 4b 24 89 53 1c 89 43 24 89 4b 20 8b 43 20 c7 43 2c 00 00 00 00 23 75 e8 8b 50 68 89 53 28 8b 54 b3 20 <8b> 72 48 8b 7a 4c 8b 55 08 89 b3 84 00 00 00 89 bb 88 00 00 00 EIP: [] nilfs_load_super_block+0x17e/0x280 [nilfs2] SS:ESP 0068:ca9bbdcc CR2: 0000000000000048 This turned out due to a defect in an error path which runs if the calculated location of the secondary super block was invalid. This patch fixes it and eliminates the reported oops. Reported-by: Slicky Devil Signed-off-by: Ryusuke Konishi Tested-by: Slicky Devil Cc: [2.6.30+] Signed-off-by: Andrew Morton Signed-off-by: Linus Torvalds --- diff --git a/fs/nilfs2/the_nilfs.c b/fs/nilfs2/the_nilfs.c index 8a759016c2e3..501b7f8b739f 100644 --- a/fs/nilfs2/the_nilfs.c +++ b/fs/nilfs2/the_nilfs.c @@ -521,6 +521,7 @@ static int nilfs_load_super_block(struct the_nilfs *nilfs, brelse(sbh[1]); sbh[1] = NULL; sbp[1] = NULL; + valid[1] = 0; swp = 0; } if (!valid[swp]) {