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| author | Chris Mason <clm@fb.com> | 2015-12-15 18:15:32 +0300 |
|---|---|---|
| committer | Chris Mason <clm@fb.com> | 2015-12-15 20:09:33 +0300 |
| commit | 1b9b922a3a601b0c99a095ffafed61fcf6ebe0b7 (patch) | |
| tree | ee56419f06db9a27f238181b5572cfa3b7cd0027 /fs | |
| parent | dba72cb30b6a4811038128c8a98b268d18ca60fe (diff) | |
| download | linux-1b9b922a3a601b0c99a095ffafed61fcf6ebe0b7.tar.xz | |
Btrfs: check for empty bitmap list in setup_cluster_bitmaps
Dave Jones found a warning from kasan in setup_cluster_bitmaps()
==================================================================
BUG: KASAN: stack-out-of-bounds in setup_cluster_bitmap+0xc4/0x5a0 at
addr ffff88039bef6828
Read of size 8 by task nfsd/1009
page:ffffea000e6fbd80 count:0 mapcount:0 mapping: (null)
index:0x0
flags: 0x8000000000000000()
page dumped because: kasan: bad access detected
CPU: 1 PID: 1009 Comm: nfsd Tainted: G W
4.4.0-rc3-backup-debug+ #1
ffff880065647b50 000000006bb712c2 ffff88039bef6640 ffffffffa680a43e
0000004559c00000 ffff88039bef66c8 ffffffffa62638d1 ffffffffa61121c0
ffff8803a5769de8 0000000000000296 ffff8803a5769df0 0000000000046280
Call Trace:
[<ffffffffa680a43e>] dump_stack+0x4b/0x6d
[<ffffffffa62638d1>] kasan_report_error+0x501/0x520
[<ffffffffa61121c0>] ? debug_show_all_locks+0x1e0/0x1e0
[<ffffffffa6263948>] kasan_report+0x58/0x60
[<ffffffffa6814b00>] ? rb_last+0x10/0x40
[<ffffffffa66f8af4>] ? setup_cluster_bitmap+0xc4/0x5a0
[<ffffffffa6262ead>] __asan_load8+0x5d/0x70
[<ffffffffa66f8af4>] setup_cluster_bitmap+0xc4/0x5a0
[<ffffffffa66f675a>] ? setup_cluster_no_bitmap+0x6a/0x400
[<ffffffffa66fcd16>] btrfs_find_space_cluster+0x4b6/0x640
[<ffffffffa66fc860>] ? btrfs_alloc_from_cluster+0x4e0/0x4e0
[<ffffffffa66fc36e>] ? btrfs_return_cluster_to_free_space+0x9e/0xb0
[<ffffffffa702dc37>] ? _raw_spin_unlock+0x27/0x40
[<ffffffffa666a1a1>] find_free_extent+0xba1/0x1520
Andrey noticed this was because we were doing list_first_entry on a list
that might be empty. Rework the tests a bit so we don't do that.
Signed-off-by: Chris Mason <clm@fb.com>
Reprorted-by: Andrey Ryabinin <ryabinin.a.a@gmail.com>
Reported-by: Dave Jones <dsj@fb.com>
Diffstat (limited to 'fs')
| -rw-r--r-- | fs/btrfs/free-space-cache.c | 8 |
1 files changed, 5 insertions, 3 deletions
diff --git a/fs/btrfs/free-space-cache.c b/fs/btrfs/free-space-cache.c index 0948d34cb84a..e6fc7d9e65b1 100644 --- a/fs/btrfs/free-space-cache.c +++ b/fs/btrfs/free-space-cache.c @@ -2972,7 +2972,7 @@ setup_cluster_bitmap(struct btrfs_block_group_cache *block_group, u64 cont1_bytes, u64 min_bytes) { struct btrfs_free_space_ctl *ctl = block_group->free_space_ctl; - struct btrfs_free_space *entry; + struct btrfs_free_space *entry = NULL; int ret = -ENOSPC; u64 bitmap_offset = offset_to_bitmap(ctl, offset); @@ -2983,8 +2983,10 @@ setup_cluster_bitmap(struct btrfs_block_group_cache *block_group, * The bitmap that covers offset won't be in the list unless offset * is just its start offset. */ - entry = list_first_entry(bitmaps, struct btrfs_free_space, list); - if (entry->offset != bitmap_offset) { + if (!list_empty(bitmaps)) + entry = list_first_entry(bitmaps, struct btrfs_free_space, list); + + if (!entry || entry->offset != bitmap_offset) { entry = tree_search_offset(ctl, bitmap_offset, 1, 0); if (entry && list_empty(&entry->list)) list_add(&entry->list, bitmaps); |