From patchwork Sat Aug 24 09:58:23 2024 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Qu Wenruo X-Patchwork-Id: 13776399 Received: from smtp-out2.suse.de (smtp-out2.suse.de [195.135.223.131]) (using TLSv1.2 with cipher ECDHE-RSA-AES128-GCM-SHA256 (128/128 bits)) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id E09302F29 for ; Sat, 24 Aug 2024 09:58:50 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=195.135.223.131 ARC-Seal: i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1724493533; cv=none; b=WsVl9LYWkz6yGx+aHaQ117tKgxRc2OyYf6+PbBkE5+H5P02ZqdVJR89CDyA7Cht2BKd5tyoQ57V93zgfoVk/vY1wVHPxFSmcC6pKOQZpXBwiEMADa7E5ipJtmhHiACvSnrUN++ORYaDGZV4ASgcT2zRzSnXqEIFi/nlJXs6SuSY= ARC-Message-Signature: i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1724493533; c=relaxed/simple; bh=IoMhtKnL7qnSksD8I0g9LC6W1Ske8s9iMAZ+QVOBW2w=; h=From:To:Cc:Subject:Date:Message-ID:MIME-Version; b=FQaa6jI6BwvuUgwbAaHGvU+D4CFGuFCVbJeYufKkK3VddVyACOkSMs/3zV6djCoIap8eguGKVKuSA9VRiQI3+XupLcpzqTf6QIEoE84cl26nA6JsRFuujYQaVJQVzdCTXQnNOu8KafpcEnPGtqyKwB1aFO7CfmMdogCaAxX2dFo= ARC-Authentication-Results: i=1; smtp.subspace.kernel.org; dmarc=pass (p=quarantine dis=none) header.from=suse.com; spf=pass smtp.mailfrom=suse.com; dkim=pass (1024-bit key) header.d=suse.com header.i=@suse.com header.b=leFA9zl2; dkim=pass (1024-bit key) header.d=suse.com header.i=@suse.com header.b=jRBJkjjZ; arc=none smtp.client-ip=195.135.223.131 Authentication-Results: smtp.subspace.kernel.org; dmarc=pass (p=quarantine dis=none) header.from=suse.com Authentication-Results: smtp.subspace.kernel.org; spf=pass smtp.mailfrom=suse.com Authentication-Results: smtp.subspace.kernel.org; dkim=pass (1024-bit key) header.d=suse.com header.i=@suse.com header.b="leFA9zl2"; dkim=pass (1024-bit key) header.d=suse.com header.i=@suse.com header.b="jRBJkjjZ" Received: from imap1.dmz-prg2.suse.org (imap1.dmz-prg2.suse.org [IPv6:2a07:de40:b281:104:10:150:64:97]) (using TLSv1.3 with cipher TLS_AES_256_GCM_SHA384 (256/256 bits) key-exchange X25519 server-signature RSA-PSS (4096 bits) server-digest SHA256) (No client certificate requested) by smtp-out2.suse.de (Postfix) with ESMTPS id F3B741FE5F; Sat, 24 Aug 2024 09:58:45 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=suse.com; s=susede1; t=1724493529; h=from:from:reply-to:date:date:message-id:message-id:to:to:cc:cc: mime-version:mime-version: content-transfer-encoding:content-transfer-encoding; bh=ulzZgMRTRGkGrpckSJOFRvaqSx7cjbuFOe9zolUuHjE=; b=leFA9zl2LLXQ/rkNosNuk0j0FkHHwA5ieapm3lBi/WmuAdhSjsZga4q32144Ht61VIYOBa /pVSZjTpdJPkGVKEsOH0EbQ6fwR3AOZ07XtTfM/hcy8MmzTGx0ZUz6fkwf/jGnc5PEM2sQ zpfUYwxb/3KjmV2TtpOlEyy5NGpEKzA= Authentication-Results: smtp-out2.suse.de; dkim=pass header.d=suse.com header.s=susede1 header.b=jRBJkjjZ DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=suse.com; s=susede1; t=1724493526; h=from:from:reply-to:date:date:message-id:message-id:to:to:cc:cc: mime-version:mime-version: content-transfer-encoding:content-transfer-encoding; bh=ulzZgMRTRGkGrpckSJOFRvaqSx7cjbuFOe9zolUuHjE=; b=jRBJkjjZOqzOZC3nYi/6wffOSBu5RzRxZwmrl5HjZgNO71YO+NOQFOZFcUjofX23xGtwO/ iBUb3PbBHgyc5py4/W3Ec4hbI3hUfYUXUVD1z263VorWzpLMMivvR9sGTlxLdozIeKwVsP 4is0wd1jK0g06NI9UrsrvRTq3A6Fo2A= Received: from imap1.dmz-prg2.suse.org (localhost [127.0.0.1]) (using TLSv1.3 with cipher TLS_AES_256_GCM_SHA384 (256/256 bits) key-exchange X25519 server-signature RSA-PSS (4096 bits) server-digest SHA256) (No client certificate requested) by imap1.dmz-prg2.suse.org (Postfix) with ESMTPS id 0544D13A66; Sat, 24 Aug 2024 09:58:44 +0000 (UTC) Received: from dovecot-director2.suse.de ([2a07:de40:b281:106:10:150:64:167]) by imap1.dmz-prg2.suse.org with ESMTPSA id 3T+lLtSuyWY6JgAAD6G6ig (envelope-from ); Sat, 24 Aug 2024 09:58:44 +0000 From: Qu Wenruo To: linux-btrfs@vger.kernel.org Cc: David Sterba Subject: [PATCH v4] btrfs: fix a use-after-free bug when hitting errors inside btrfs_submit_chunk() Date: Sat, 24 Aug 2024 19:28:23 +0930 Message-ID: X-Mailer: git-send-email 2.46.0 Precedence: bulk X-Mailing-List: linux-btrfs@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 X-Rspamd-Queue-Id: F3B741FE5F X-Spam-Score: -5.01 X-Rspamd-Action: no action X-Spamd-Result: default: False [-5.01 / 50.00]; BAYES_HAM(-3.00)[100.00%]; DWL_DNSWL_MED(-2.00)[suse.com:dkim]; MID_CONTAINS_FROM(1.00)[]; NEURAL_HAM_LONG(-1.00)[-1.000]; R_MISSING_CHARSET(0.50)[]; R_DKIM_ALLOW(-0.20)[suse.com:s=susede1]; NEURAL_HAM_SHORT(-0.20)[-1.000]; MIME_GOOD(-0.10)[text/plain]; MX_GOOD(-0.01)[]; RBL_SPAMHAUS_BLOCKED_OPENRESOLVER(0.00)[2a07:de40:b281:104:10:150:64:97:from]; RECEIVED_SPAMHAUS_BLOCKED_OPENRESOLVER(0.00)[2a07:de40:b281:106:10:150:64:167:received]; FUZZY_BLOCKED(0.00)[rspamd.com]; ARC_NA(0.00)[]; TO_DN_SOME(0.00)[]; FROM_HAS_DN(0.00)[]; MIME_TRACE(0.00)[0:+]; RCPT_COUNT_TWO(0.00)[2]; DKIM_SIGNED(0.00)[suse.com:s=susede1]; RCVD_COUNT_TWO(0.00)[2]; RCVD_TLS_ALL(0.00)[]; DKIM_TRACE(0.00)[suse.com:+]; RCVD_VIA_SMTP_AUTH(0.00)[]; FROM_EQ_ENVFROM(0.00)[]; TO_MATCH_ENVRCPT_ALL(0.00)[]; SPAMHAUS_XBL(0.00)[2a07:de40:b281:104:10:150:64:97:from]; DBL_BLOCKED_OPENRESOLVER(0.00)[imap1.dmz-prg2.suse.org:rdns,imap1.dmz-prg2.suse.org:helo,suse.com:dkim,suse.com:mid,suse.com:email,opensuse.org:url,suse.cz:email] X-Rspamd-Server: rspamd1.dmz-prg2.suse.org X-Spam-Flag: NO X-Spam-Level: [BUG] There is an internal report that KASAN is reporting use-after-free, with the following backtrace: ================================================================== BUG: KASAN: slab-use-after-free in btrfs_check_read_bio+0xa68/0xb70 [btrfs] Read of size 4 at addr ffff8881117cec28 by task kworker/u16:2/45 CPU: 1 UID: 0 PID: 45 Comm: kworker/u16:2 Not tainted 6.11.0-rc2-next-20240805-default+ #76 Hardware name: QEMU Standard PC (i440FX + PIIX, 1996), BIOS rel-1.16.2-3-gd478f380-rebuilt.opensuse.org 04/01/2014 Workqueue: btrfs-endio btrfs_end_bio_work [btrfs] Call Trace: dump_stack_lvl+0x61/0x80 print_address_description.constprop.0+0x5e/0x2f0 print_report+0x118/0x216 kasan_report+0x11d/0x1f0 btrfs_check_read_bio+0xa68/0xb70 [btrfs] process_one_work+0xce0/0x12a0 worker_thread+0x717/0x1250 kthread+0x2e3/0x3c0 ret_from_fork+0x2d/0x70 ret_from_fork_asm+0x11/0x20 Allocated by task 20917: kasan_save_stack+0x37/0x60 kasan_save_track+0x10/0x30 __kasan_slab_alloc+0x7d/0x80 kmem_cache_alloc_noprof+0x16e/0x3e0 mempool_alloc_noprof+0x12e/0x310 bio_alloc_bioset+0x3f0/0x7a0 btrfs_bio_alloc+0x2e/0x50 [btrfs] submit_extent_page+0x4d1/0xdb0 [btrfs] btrfs_do_readpage+0x8b4/0x12a0 [btrfs] btrfs_readahead+0x29a/0x430 [btrfs] read_pages+0x1a7/0xc60 page_cache_ra_unbounded+0x2ad/0x560 filemap_get_pages+0x629/0xa20 filemap_read+0x335/0xbf0 vfs_read+0x790/0xcb0 ksys_read+0xfd/0x1d0 do_syscall_64+0x6d/0x140 entry_SYSCALL_64_after_hwframe+0x4b/0x53 Freed by task 20917: kasan_save_stack+0x37/0x60 kasan_save_track+0x10/0x30 kasan_save_free_info+0x37/0x50 __kasan_slab_free+0x4b/0x60 kmem_cache_free+0x214/0x5d0 bio_free+0xed/0x180 end_bbio_data_read+0x1cc/0x580 [btrfs] btrfs_submit_chunk+0x98d/0x1880 [btrfs] btrfs_submit_bio+0x33/0x70 [btrfs] submit_one_bio+0xd4/0x130 [btrfs] submit_extent_page+0x3ea/0xdb0 [btrfs] btrfs_do_readpage+0x8b4/0x12a0 [btrfs] btrfs_readahead+0x29a/0x430 [btrfs] read_pages+0x1a7/0xc60 page_cache_ra_unbounded+0x2ad/0x560 filemap_get_pages+0x629/0xa20 filemap_read+0x335/0xbf0 vfs_read+0x790/0xcb0 ksys_read+0xfd/0x1d0 do_syscall_64+0x6d/0x140 entry_SYSCALL_64_after_hwframe+0x4b/0x53 [CAUSE] Although I can not reproduce the error, the report itself is good enough to pin down the cause. The call trace is the regular endio workqueue context, but the free-by-task trace is showing that during btrfs_submit_chunk() we already hit a critical error, and is calling btrfs_bio_end_io() to error out. And the original endio function called bio_put() to free the whole bio. This means a double freeing thus causing use-after-free, e.g: 1. Enter btrfs_submit_bio() with a read bio The read bio length is 128K, crossing two 64K stripes. 2. The first run of btrfs_submit_chunk() 2.1 Call btrfs_map_block(), which returns 64K 2.2 Call btrfs_split_bio() Now there are two bios, one referring to the first 64K, the other referring to the second 64K. 2.3 The first half is submitted. 3. The second run of btrfs_submit_chunk() 3.1 Call btrfs_map_block(), which by somehow failed Now we call btrfs_bio_end_io() to handle the error 3.2 btrfs_bio_end_io() calls the original endio function Which is end_bbio_data_read(), and it calls bio_put() for the original bio. Now the original bio is freed. 4. The submitted first 64K bio finished Now we call into btrfs_check_read_bio() and tries to advance the bio iter. But since the original bio (thus its iter) is already freed, we trigger the above use-after free. And even if the memory is not poisoned/corrupted, we will later call the original endio function, causing a double freeing. [FIX] Instead of calling btrfs_bio_end_io(), call btrfs_orig_bbio_end_io(), which has the extra check on split bios and do the proper refcounting for cloned bios. Furthermore there is already one extra btrfs_cleanup_bio() call, but that is duplicated to btrfs_orig_bbio_end_io() call, so remove that tag completely. Reported-by: David Sterba Fixes: 852eee62d31a ("btrfs: allow btrfs_submit_bio to split bios") Signed-off-by: Qu Wenruo Reviewed-by: Josef Bacik Reviewed-by: David Sterba --- Changelog: v4: - Fix a case where the endio function is never called If we have split the bbio and hit a critical error, we have to end both the current and the remaining bbio. As the remaining one will never be submitted, thus pending_ios will never reach 0. v3: - Fix a double free if we go into fail_put_bio() tag By removing the tag and the btrfs_cleanup_bio() call completely. v2: - Remove the unused variable @orig_bbio --- fs/btrfs/bio.c | 26 ++++++++++++++++++-------- 1 file changed, 18 insertions(+), 8 deletions(-) diff --git a/fs/btrfs/bio.c b/fs/btrfs/bio.c index 0ef70fce85ff..f6cb58d7f16a 100644 --- a/fs/btrfs/bio.c +++ b/fs/btrfs/bio.c @@ -668,7 +668,6 @@ static bool btrfs_submit_chunk(struct btrfs_bio *bbio, int mirror_num) { struct btrfs_inode *inode = bbio->inode; struct btrfs_fs_info *fs_info = bbio->fs_info; - struct btrfs_bio *orig_bbio = bbio; struct bio *bio = &bbio->bio; u64 logical = bio->bi_iter.bi_sector << SECTOR_SHIFT; u64 length = bio->bi_iter.bi_size; @@ -709,7 +708,7 @@ static bool btrfs_submit_chunk(struct btrfs_bio *bbio, int mirror_num) bbio->saved_iter = bio->bi_iter; ret = btrfs_lookup_bio_sums(bbio); if (ret) - goto fail_put_bio; + goto fail; } if (btrfs_op(bio) == BTRFS_MAP_WRITE) { @@ -743,13 +742,13 @@ static bool btrfs_submit_chunk(struct btrfs_bio *bbio, int mirror_num) ret = btrfs_bio_csum(bbio); if (ret) - goto fail_put_bio; + goto fail; } else if (use_append || (btrfs_is_zoned(fs_info) && inode && inode->flags & BTRFS_INODE_NODATASUM)) { ret = btrfs_alloc_dummy_sum(bbio); if (ret) - goto fail_put_bio; + goto fail; } } @@ -757,12 +756,23 @@ static bool btrfs_submit_chunk(struct btrfs_bio *bbio, int mirror_num) done: return map_length == length; -fail_put_bio: - if (map_length < length) - btrfs_cleanup_bio(bbio); fail: btrfs_bio_counter_dec(fs_info); - btrfs_bio_end_io(orig_bbio, ret); + /* + * We have split the original bbio, now we have to end both the current + * @bbio and remaining one, as the remaining one will never be submitted. + */ + if (map_length < length) { + struct btrfs_bio *remaining = bbio->private; + + ASSERT(bbio->bio.bi_pool == &btrfs_clone_bioset); + ASSERT(remaining); + + remaining->bio.bi_status = ret; + btrfs_orig_bbio_end_io(remaining); + } + bbio->bio.bi_status = ret; + btrfs_orig_bbio_end_io(bbio); /* Do not submit another chunk */ return true; }