On Mon, Jun 17, 2024 at 09:37:01AM +0800, Baokun Li wrote: > Hi Sasha, > > Thanks for adapting this patch to the stable branch. Just one nit. > > On 2024/6/16 10:05, Sasha Levin wrote: > > This is a note to let you know that I've just added the patch titled > > > > ext4: fix slab-out-of-bounds in ext4_mb_find_good_group_avg_frag_lists() > > > > to the 6.9-stable tree which can be found at: > > http://www.kernel.org/git/?p=linux/kernel/git/stable/stable-queue.git;a=summary > > > > The filename of the patch is: > > ext4-fix-slab-out-of-bounds-in-ext4_mb_find_good_gro.patch > > and it can be found in the queue-6.9 subdirectory. > > > > If you, or anyone else, feels it should not be added to the stable tree, > > please let <stable@xxxxxxxxxxxxxxx> know about it. > > > > > > > > commit 84cee2d2394a43766dd2990edac8a4a05817ef7b > > Author: Baokun Li <libaokun1@xxxxxxxxxx> > > Date: Tue Mar 19 19:33:20 2024 +0800 > > > > ext4: fix slab-out-of-bounds in ext4_mb_find_good_group_avg_frag_lists() > > [ Upstream commit 13df4d44a3aaabe61cd01d277b6ee23ead2a5206 ] > > We can trigger a slab-out-of-bounds with the following commands: > > mkfs.ext4 -F /dev/$disk 10G > > mount /dev/$disk /tmp/test > > echo 2147483647 > /sys/fs/ext4/$disk/mb_group_prealloc > > echo test > /tmp/test/file && sync > > ================================================================== > > BUG: KASAN: slab-out-of-bounds in ext4_mb_find_good_group_avg_frag_lists+0x8a/0x200 [ext4] > > Read of size 8 at addr ffff888121b9d0f0 by task kworker/u2:0/11 > > CPU: 0 PID: 11 Comm: kworker/u2:0 Tainted: GL 6.7.0-next-20240118 #521 > > Call Trace: > > dump_stack_lvl+0x2c/0x50 > > kasan_report+0xb6/0xf0 > > ext4_mb_find_good_group_avg_frag_lists+0x8a/0x200 [ext4] > > ext4_mb_regular_allocator+0x19e9/0x2370 [ext4] > > ext4_mb_new_blocks+0x88a/0x1370 [ext4] > > ext4_ext_map_blocks+0x14f7/0x2390 [ext4] > > ext4_map_blocks+0x569/0xea0 [ext4] > > ext4_do_writepages+0x10f6/0x1bc0 [ext4] > > [...] > > ================================================================== > > The flow of issue triggering is as follows: > > // Set s_mb_group_prealloc to 2147483647 via sysfs > > ext4_mb_new_blocks > > ext4_mb_normalize_request > > ext4_mb_normalize_group_request > > ac->ac_g_ex.fe_len = EXT4_SB(sb)->s_mb_group_prealloc > > ext4_mb_regular_allocator > > ext4_mb_choose_next_group > > ext4_mb_choose_next_group_best_avail > > mb_avg_fragment_size_order > > order = fls(len) - 2 = 29 > > ext4_mb_find_good_group_avg_frag_lists > > frag_list = &sbi->s_mb_avg_fragment_size[order] > > if (list_empty(frag_list)) // Trigger SOOB! > > At 4k block size, the length of the s_mb_avg_fragment_size list is 14, > > but an oversized s_mb_group_prealloc is set, causing slab-out-of-bounds > > to be triggered by an attempt to access an element at index 29. > > Add a new attr_id attr_clusters_in_group with values in the range > > [0, sbi->s_clusters_per_group] and declare mb_group_prealloc as > > that type to fix the issue. In addition avoid returning an order > > from mb_avg_fragment_size_order() greater than MB_NUM_ORDERS(sb) > > and reduce some useless loops. > > Fixes: 7e170922f06b ("ext4: Add allocation criteria 1.5 (CR1_5)") > > CC: stable@xxxxxxxxxxxxxxx > > Signed-off-by: Baokun Li <libaokun1@xxxxxxxxxx> > > Reviewed-by: Jan Kara <jack@xxxxxxx> > > Reviewed-by: Ojaswin Mujoo <ojaswin@xxxxxxxxxxxxx> > > Link: https://lore.kernel.org/r/20240319113325.3110393-5-libaokun1@xxxxxxxxxx > > Signed-off-by: Theodore Ts'o <tytso@xxxxxxx> > > Signed-off-by: Sasha Levin <sashal@xxxxxxxxxx> > > > > diff --git a/fs/ext4/mballoc.c b/fs/ext4/mballoc.c > > index 714f83632e3f9..66b5a68b0254e 100644 > > --- a/fs/ext4/mballoc.c > > +++ b/fs/ext4/mballoc.c > > @@ -831,6 +831,8 @@ static int mb_avg_fragment_size_order(struct super_block *sb, ext4_grpblk_t len) > > return 0; > > if (order == MB_NUM_ORDERS(sb)) > > order--; > > + if (WARN_ON_ONCE(order > MB_NUM_ORDERS(sb))) > > + order = MB_NUM_ORDERS(sb) - 1; > > return order; > > } > > @@ -1008,6 +1010,8 @@ static void ext4_mb_choose_next_group_best_avail(struct ext4_allocation_context > > * goal length. > > */ > > order = fls(ac->ac_g_ex.fe_len) - 1; > > + if (WARN_ON_ONCE(order - 1 > MB_NUM_ORDERS(ac->ac_sb))) > > + order = MB_NUM_ORDERS(ac->ac_sb); > > min_order = order - sbi->s_mb_best_avail_max_trim_order; > > if (min_order < 0) > > min_order = 0; > > diff --git a/fs/ext4/sysfs.c b/fs/ext4/sysfs.c > > index 295ea9a32de91..ca66e33f61815 100644 > > --- a/fs/ext4/sysfs.c > > +++ b/fs/ext4/sysfs.c > > @@ -29,6 +29,7 @@ typedef enum { > > attr_trigger_test_error, > > attr_first_error_time, > > attr_last_error_time, > > + attr_clusters_in_group, > > attr_feature, > > attr_pointer_ui, > > attr_pointer_ul, > > @@ -207,13 +208,14 @@ EXT4_ATTR_FUNC(sra_exceeded_retry_limit, 0444); > > EXT4_ATTR_OFFSET(inode_readahead_blks, 0644, inode_readahead, > > ext4_sb_info, s_inode_readahead_blks); > > +EXT4_ATTR_OFFSET(mb_group_prealloc, 0644, clusters_in_group, > > + ext4_sb_info, s_mb_group_prealloc); > > EXT4_RW_ATTR_SBI_UI(inode_goal, s_inode_goal); > > EXT4_RW_ATTR_SBI_UI(mb_stats, s_mb_stats); > > EXT4_RW_ATTR_SBI_UI(mb_max_to_scan, s_mb_max_to_scan); > > EXT4_RW_ATTR_SBI_UI(mb_min_to_scan, s_mb_min_to_scan); > > EXT4_RW_ATTR_SBI_UI(mb_order2_req, s_mb_order2_reqs); > > EXT4_RW_ATTR_SBI_UI(mb_stream_req, s_mb_stream_request); > > -EXT4_RW_ATTR_SBI_UI(mb_group_prealloc, s_mb_group_prealloc); > > EXT4_RW_ATTR_SBI_UI(mb_max_linear_groups, s_mb_max_linear_groups); > > EXT4_RW_ATTR_SBI_UI(extent_max_zeroout_kb, s_extent_max_zeroout_kb); > > EXT4_ATTR(trigger_fs_error, 0200, trigger_test_error); > > @@ -376,6 +378,7 @@ static ssize_t ext4_generic_attr_show(struct ext4_attr *a, > > switch (a->attr_id) { > > case attr_inode_readahead: > > + case attr_clusters_in_group: > > case attr_pointer_ui: > > if (a->attr_ptr == ptr_ext4_super_block_offset) > > return sysfs_emit(buf, "%u\n", le32_to_cpup(ptr)); > > @@ -459,6 +462,14 @@ static ssize_t ext4_attr_store(struct kobject *kobj, > > else > > *((unsigned int *) ptr) = t; > > return len; > > + case attr_clusters_in_group: > Since commit f536808adcc3 "ext4: refactor out ext4_generic_attr_store()" > is not backported to stable, the following judgement needs to be added > here: > > if (!ptr) > return 0; > > The patch for the 6.6-stable tree has the same problem. Thanks, I've dropped this from both queues now, can you resend it with a fixed up version? thanks, greg k-h
