On 2024/1/28 07:06, gregkh@xxxxxxxxxxxxxxxxxxx wrote:
The patch below does not apply to the 6.6-stable tree. If someone wants it applied there, or to any other stable or longterm tree, then please email the backport, including the original git commit id to <stable@xxxxxxxxxxxxxxx>. To reproduce the conflict and resubmit, you may use the following commands: git fetch https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git/ linux-6.6.y git checkout FETCH_HEAD git cherry-pick -x c # <resolve conflicts, build, test, etc.> git commit -s git send-email --to '<stable@xxxxxxxxxxxxxxx>' --in-reply-to '2024012740-mating-boxing-dd93@gregkh' --subject-prefix 'PATCH 6.6.y' HEAD^..
Great new hints on the conflict resolve steps, especially for guys like me, who is not familiar with stable kernels.
Would backport it soon. Thanks, Qu
Possible dependencies: f546c4282673 ("btrfs: scrub: avoid use-after-free when chunk length is not 64K aligned") thanks, greg k-h ------------------ original commit in Linus's tree ------------------ From f546c4282673497a06ecb6190b50ae7f6c85b02f Mon Sep 17 00:00:00 2001 From: Qu Wenruo <wqu@xxxxxxxx> Date: Wed, 17 Jan 2024 11:02:25 +1030 Subject: [PATCH] btrfs: scrub: avoid use-after-free when chunk length is not 64K aligned [BUG] There is a bug report that, on a ext4-converted btrfs, scrub leads to various problems, including: - "unable to find chunk map" errors BTRFS info (device vdb): scrub: started on devid 1 BTRFS critical (device vdb): unable to find chunk map for logical 2214744064 length 4096 BTRFS critical (device vdb): unable to find chunk map for logical 2214744064 length 45056 This would lead to unrepariable errors. - Use-after-free KASAN reports: ================================================================== BUG: KASAN: slab-use-after-free in __blk_rq_map_sg+0x18f/0x7c0 Read of size 8 at addr ffff8881013c9040 by task btrfs/909 CPU: 0 PID: 909 Comm: btrfs Not tainted 6.7.0-x64v3-dbg #11 c50636e9419a8354555555245df535e380563b2b Hardware name: QEMU Standard PC (Q35 + ICH9, 2009), BIOS 2023.11-2 12/24/2023 Call Trace: <TASK> dump_stack_lvl+0x43/0x60 print_report+0xcf/0x640 kasan_report+0xa6/0xd0 __blk_rq_map_sg+0x18f/0x7c0 virtblk_prep_rq.isra.0+0x215/0x6a0 [virtio_blk 19a65eeee9ae6fcf02edfad39bb9ddee07dcdaff] virtio_queue_rqs+0xc4/0x310 [virtio_blk 19a65eeee9ae6fcf02edfad39bb9ddee07dcdaff] blk_mq_flush_plug_list.part.0+0x780/0x860 __blk_flush_plug+0x1ba/0x220 blk_finish_plug+0x3b/0x60 submit_initial_group_read+0x10a/0x290 [btrfs e57987a360bed82fe8756dcd3e0de5406ccfe965] flush_scrub_stripes+0x38e/0x430 [btrfs e57987a360bed82fe8756dcd3e0de5406ccfe965] scrub_stripe+0x82a/0xae0 [btrfs e57987a360bed82fe8756dcd3e0de5406ccfe965] scrub_chunk+0x178/0x200 [btrfs e57987a360bed82fe8756dcd3e0de5406ccfe965] scrub_enumerate_chunks+0x4bc/0xa30 [btrfs e57987a360bed82fe8756dcd3e0de5406ccfe965] btrfs_scrub_dev+0x398/0x810 [btrfs e57987a360bed82fe8756dcd3e0de5406ccfe965] btrfs_ioctl+0x4b9/0x3020 [btrfs e57987a360bed82fe8756dcd3e0de5406ccfe965] __x64_sys_ioctl+0xbd/0x100 do_syscall_64+0x5d/0xe0 entry_SYSCALL_64_after_hwframe+0x63/0x6b RIP: 0033:0x7f47e5e0952b - Crash, mostly due to above use-after-free [CAUSE] The converted fs has the following data chunk layout: item 2 key (FIRST_CHUNK_TREE CHUNK_ITEM 2214658048) itemoff 16025 itemsize 80 length 86016 owner 2 stripe_len 65536 type DATA|single For above logical bytenr 2214744064, it's at the chunk end (2214658048 + 86016 = 2214744064). This means btrfs_submit_bio() would split the bio, and trigger endio function for both of the two halves. However scrub_submit_initial_read() would only expect the endio function to be called once, not any more. This means the first endio function would already free the bbio::bio, leaving the bvec freed, thus the 2nd endio call would lead to use-after-free. [FIX] - Make sure scrub_read_endio() only updates bits in its range Since we may read less than 64K at the end of the chunk, we should not touch the bits beyond chunk boundary. - Make sure scrub_submit_initial_read() only to read the chunk range This is done by calculating the real number of sectors we need to read, and add sector-by-sector to the bio. Thankfully the scrub read repair path won't need extra fixes: - scrub_stripe_submit_repair_read() With above fixes, we won't update error bit for range beyond chunk, thus scrub_stripe_submit_repair_read() should never submit any read beyond the chunk. Reported-by: Rongrong <i@xxxxxxxx> Fixes: e02ee89baa66 ("btrfs: scrub: switch scrub_simple_mirror() to scrub_stripe infrastructure") Tested-by: Rongrong <i@xxxxxxxx> Reviewed-by: Johannes Thumshirn <johannes.thumshirn@xxxxxxx> Signed-off-by: Qu Wenruo <wqu@xxxxxxxx> Signed-off-by: David Sterba <dsterba@xxxxxxxx> diff --git a/fs/btrfs/scrub.c b/fs/btrfs/scrub.c index a01807cbd4d4..2d81b1a18a04 100644 --- a/fs/btrfs/scrub.c +++ b/fs/btrfs/scrub.c @@ -1098,12 +1098,22 @@ static void scrub_stripe_read_repair_worker(struct work_struct *work) static void scrub_read_endio(struct btrfs_bio *bbio) { struct scrub_stripe *stripe = bbio->private; + struct bio_vec *bvec; + int sector_nr = calc_sector_number(stripe, bio_first_bvec_all(&bbio->bio)); + int num_sectors; + u32 bio_size = 0; + int i; + + ASSERT(sector_nr < stripe->nr_sectors); + bio_for_each_bvec_all(bvec, &bbio->bio, i) + bio_size += bvec->bv_len; + num_sectors = bio_size >> stripe->bg->fs_info->sectorsize_bits;if (bbio->bio.bi_status) {- bitmap_set(&stripe->io_error_bitmap, 0, stripe->nr_sectors); - bitmap_set(&stripe->error_bitmap, 0, stripe->nr_sectors); + bitmap_set(&stripe->io_error_bitmap, sector_nr, num_sectors); + bitmap_set(&stripe->error_bitmap, sector_nr, num_sectors); } else { - bitmap_clear(&stripe->io_error_bitmap, 0, stripe->nr_sectors); + bitmap_clear(&stripe->io_error_bitmap, sector_nr, num_sectors); } bio_put(&bbio->bio); if (atomic_dec_and_test(&stripe->pending_io)) { @@ -1701,6 +1711,9 @@ static void scrub_submit_initial_read(struct scrub_ctx *sctx, { struct btrfs_fs_info *fs_info = sctx->fs_info; struct btrfs_bio *bbio; + unsigned int nr_sectors = min(BTRFS_STRIPE_LEN, stripe->bg->start + + stripe->bg->length - stripe->logical) >> + fs_info->sectorsize_bits; int mirror = stripe->mirror_num;ASSERT(stripe->bg);@@ -1715,14 +1728,16 @@ static void scrub_submit_initial_read(struct scrub_ctx *sctx, bbio = btrfs_bio_alloc(SCRUB_STRIPE_PAGES, REQ_OP_READ, fs_info, scrub_read_endio, stripe);- /* Read the whole stripe. */bbio->bio.bi_iter.bi_sector = stripe->logical >> SECTOR_SHIFT; - for (int i = 0; i < BTRFS_STRIPE_LEN >> PAGE_SHIFT; i++) { + /* Read the whole range inside the chunk boundary. */ + for (unsigned int cur = 0; cur < nr_sectors; cur++) { + struct page *page = scrub_stripe_get_page(stripe, cur); + unsigned int pgoff = scrub_stripe_get_page_offset(stripe, cur); int ret;- ret = bio_add_page(&bbio->bio, stripe->pages[i], PAGE_SIZE, 0);+ ret = bio_add_page(&bbio->bio, page, fs_info->sectorsize, pgoff); /* We should have allocated enough bio vectors. */ - ASSERT(ret == PAGE_SIZE); + ASSERT(ret == fs_info->sectorsize); } atomic_inc(&stripe->pending_io);
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