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| author | Qu Wenruo <wqu@suse.com> | 2019-03-18 10:48:19 +0800 |
|---|---|---|
| committer | David Sterba <dsterba@suse.com> | 2019-04-29 19:02:22 +0200 |
| commit | 10995c0491204c861948c9850939a7f4e90760a4 (patch) | |
| tree | d24eb353284bfd9dbac81b41d4317e57298717ca /fs/btrfs/relocation.c | |
| parent | d51f51bb6f3c11f3ee4120c35de8e6547ed493fc (diff) | |
| download | linux-10995c0491204c861948c9850939a7f4e90760a4.tar.bz2 | |
btrfs: reloc: Fix NULL pointer dereference due to expanded reloc_root lifespan
Commit d2311e698578 ("btrfs: relocation: Delay reloc tree deletion after
merge_reloc_roots()") expands the life span of root->reloc_root.
This breaks certain checs of fs_info->reloc_ctl. Before that commit, if
we have a root with valid reloc_root, then it's ensured to have
fs_info->reloc_ctl.
But now since reloc_root doesn't always mean a valid fs_info->reloc_ctl,
such check is unreliable and can cause the following NULL pointer
dereference:
BUG: unable to handle kernel NULL pointer dereference at 00000000000005c1
IP: btrfs_reloc_pre_snapshot+0x20/0x50 [btrfs]
PGD 0 P4D 0
Oops: 0000 [#1] SMP PTI
CPU: 0 PID: 10379 Comm: snapperd Not tainted
Call Trace:
create_pending_snapshot+0xd7/0xfc0 [btrfs]
create_pending_snapshots+0x8e/0xb0 [btrfs]
btrfs_commit_transaction+0x2ac/0x8f0 [btrfs]
btrfs_mksubvol+0x561/0x570 [btrfs]
btrfs_ioctl_snap_create_transid+0x189/0x190 [btrfs]
btrfs_ioctl_snap_create_v2+0x102/0x150 [btrfs]
btrfs_ioctl+0x5c9/0x1e60 [btrfs]
do_vfs_ioctl+0x90/0x5f0
SyS_ioctl+0x74/0x80
do_syscall_64+0x7b/0x150
entry_SYSCALL_64_after_hwframe+0x3d/0xa2
RIP: 0033:0x7fd7cdab8467
Fix it by explicitly checking fs_info->reloc_ctl other than using the
implied root->reloc_root.
Fixes: d2311e698578 ("btrfs: relocation: Delay reloc tree deletion after merge_reloc_roots")
Signed-off-by: Qu Wenruo <wqu@suse.com>
Reviewed-by: David Sterba <dsterba@suse.com>
Signed-off-by: David Sterba <dsterba@suse.com>
Diffstat (limited to 'fs/btrfs/relocation.c')
| -rw-r--r-- | fs/btrfs/relocation.c | 12 |
1 files changed, 5 insertions, 7 deletions
diff --git a/fs/btrfs/relocation.c b/fs/btrfs/relocation.c index b52fb99646dc..1af2bdf5c877 100644 --- a/fs/btrfs/relocation.c +++ b/fs/btrfs/relocation.c @@ -4668,14 +4668,12 @@ int btrfs_reloc_cow_block(struct btrfs_trans_handle *trans, void btrfs_reloc_pre_snapshot(struct btrfs_pending_snapshot *pending, u64 *bytes_to_reserve) { - struct btrfs_root *root; - struct reloc_control *rc; + struct btrfs_root *root = pending->root; + struct reloc_control *rc = root->fs_info->reloc_ctl; - root = pending->root; - if (!root->reloc_root) + if (!root->reloc_root || !rc) return; - rc = root->fs_info->reloc_ctl; if (!rc->merge_reloc_tree) return; @@ -4704,10 +4702,10 @@ int btrfs_reloc_post_snapshot(struct btrfs_trans_handle *trans, struct btrfs_root *root = pending->root; struct btrfs_root *reloc_root; struct btrfs_root *new_root; - struct reloc_control *rc; + struct reloc_control *rc = root->fs_info->reloc_ctl; int ret; - if (!root->reloc_root) + if (!root->reloc_root || !rc) return 0; rc = root->fs_info->reloc_ctl; |