Re: [PATCH v2] f2fs: fix use-after-free issue when accessing sbi->stat_info

2018-12-26 Thread Chao Yu
On 2018/12/26 13:50, Sahitya Tummala wrote:
> iput() on sbi->node_inode can update sbi->stat_info
> in the below context, if the f2fs_write_checkpoint()
> has failed with error.
> 
> f2fs_balance_fs_bg+0x1ac/0x1ec
> f2fs_write_node_pages+0x4c/0x260
> do_writepages+0x80/0xbc
> __writeback_single_inode+0xdc/0x4ac
> writeback_single_inode+0x9c/0x144
> write_inode_now+0xc4/0xec
> iput+0x194/0x22c
> f2fs_put_super+0x11c/0x1e8
> generic_shutdown_super+0x70/0xf4
> kill_block_super+0x2c/0x5c
> kill_f2fs_super+0x44/0x50
> deactivate_locked_super+0x60/0x8c
> deactivate_super+0x68/0x74
> cleanup_mnt+0x40/0x78
> 
> Fix this by moving f2fs_destroy_stats() further below iput() in
> both f2fs_put_super() and f2fs_fill_super() paths.
> 
> Signed-off-by: Sahitya Tummala 

It looks good to me now. :)

Reviewed-by: Chao Yu 

Thanks,



[PATCH v2] f2fs: fix use-after-free issue when accessing sbi->stat_info

2018-12-25 Thread Sahitya Tummala
iput() on sbi->node_inode can update sbi->stat_info
in the below context, if the f2fs_write_checkpoint()
has failed with error.

f2fs_balance_fs_bg+0x1ac/0x1ec
f2fs_write_node_pages+0x4c/0x260
do_writepages+0x80/0xbc
__writeback_single_inode+0xdc/0x4ac
writeback_single_inode+0x9c/0x144
write_inode_now+0xc4/0xec
iput+0x194/0x22c
f2fs_put_super+0x11c/0x1e8
generic_shutdown_super+0x70/0xf4
kill_block_super+0x2c/0x5c
kill_f2fs_super+0x44/0x50
deactivate_locked_super+0x60/0x8c
deactivate_super+0x68/0x74
cleanup_mnt+0x40/0x78

Fix this by moving f2fs_destroy_stats() further below iput() in
both f2fs_put_super() and f2fs_fill_super() paths.

Signed-off-by: Sahitya Tummala 
---
v2:
- cover f2fs_fill_super() also, as pointed out by Chao.

 fs/f2fs/super.c | 27 +++
 1 file changed, 15 insertions(+), 12 deletions(-)

diff --git a/fs/f2fs/super.c b/fs/f2fs/super.c
index e184ad4e..01d9548 100644
--- a/fs/f2fs/super.c
+++ b/fs/f2fs/super.c
@@ -1058,9 +1058,6 @@ static void f2fs_put_super(struct super_block *sb)
f2fs_write_checkpoint(sbi, &cpc);
}
 
-   /* f2fs_write_checkpoint can update stat informaion */
-   f2fs_destroy_stats(sbi);
-
/*
 * normally superblock is clean, so we need to release this.
 * In addition, EIO will skip do checkpoint, we need this as well.
@@ -1080,6 +1077,12 @@ static void f2fs_put_super(struct super_block *sb)
iput(sbi->node_inode);
iput(sbi->meta_inode);
 
+   /*
+* iput() can update stat information, if f2fs_write_checkpoint()
+* above failed with error.
+*/
+   f2fs_destroy_stats(sbi);
+
/* destroy f2fs internal modules */
f2fs_destroy_node_manager(sbi);
f2fs_destroy_segment_manager(sbi);
@@ -3259,30 +3262,30 @@ static int f2fs_fill_super(struct super_block *sb, void 
*data, int silent)
 
f2fs_build_gc_manager(sbi);
 
+   err = f2fs_build_stats(sbi);
+   if (err)
+   goto free_nm;
+
/* get an inode for node space */
sbi->node_inode = f2fs_iget(sb, F2FS_NODE_INO(sbi));
if (IS_ERR(sbi->node_inode)) {
f2fs_msg(sb, KERN_ERR, "Failed to read node inode");
err = PTR_ERR(sbi->node_inode);
-   goto free_nm;
+   goto free_stats;
}
 
-   err = f2fs_build_stats(sbi);
-   if (err)
-   goto free_node_inode;
-
/* read root inode and dentry */
root = f2fs_iget(sb, F2FS_ROOT_INO(sbi));
if (IS_ERR(root)) {
f2fs_msg(sb, KERN_ERR, "Failed to read root inode");
err = PTR_ERR(root);
-   goto free_stats;
+   goto free_node_inode;
}
if (!S_ISDIR(root->i_mode) || !root->i_blocks ||
!root->i_size || !root->i_nlink) {
iput(root);
err = -EINVAL;
-   goto free_stats;
+   goto free_node_inode;
}
 
sb->s_root = d_make_root(root); /* allocate root dentry */
@@ -3406,12 +3409,12 @@ static int f2fs_fill_super(struct super_block *sb, void 
*data, int silent)
 free_root_inode:
dput(sb->s_root);
sb->s_root = NULL;
-free_stats:
-   f2fs_destroy_stats(sbi);
 free_node_inode:
f2fs_release_ino_entry(sbi, true);
truncate_inode_pages_final(NODE_MAPPING(sbi));
iput(sbi->node_inode);
+free_stats:
+   f2fs_destroy_stats(sbi);
 free_nm:
f2fs_destroy_node_manager(sbi);
 free_sm:
-- 
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