From: Sasha Levin Date: Mon, 10 Aug 2015 23:05:18 +0000 (-0400) Subject: block: don't access bio->bi_error after bio_put() X-Git-Url: https://git.stricted.de/?a=commitdiff_plain;h=9b81c842355ac96097ba;p=GitHub%2Fmoto-9609%2Fandroid_kernel_motorola_exynos9610.git block: don't access bio->bi_error after bio_put() Commit 4246a0b6 ("block: add a bi_error field to struct bio") has added a few dereferences of 'bio' after a call to bio_put(). This causes use-after-frees such as: [521120.719695] BUG: KASan: use after free in dio_bio_complete+0x2b3/0x320 at addr ffff880f36b38714 [521120.720638] Read of size 4 by task mount.ocfs2/9644 [521120.721212] ============================================================================= [521120.722056] BUG kmalloc-256 (Not tainted): kasan: bad access detected [521120.722968] ----------------------------------------------------------------------------- [521120.722968] [521120.723915] Disabling lock debugging due to kernel taint [521120.724539] INFO: Slab 0xffffea003cdace00 objects=32 used=25 fp=0xffff880f36b38600 flags=0x46fffff80004080 [521120.726037] INFO: Object 0xffff880f36b38700 @offset=1792 fp=0xffff880f36b38800 [521120.726037] [521120.726974] Bytes b4 ffff880f36b386f0: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 ................ [521120.727898] Object ffff880f36b38700: 00 88 b3 36 0f 88 ff ff 00 00 d8 de 0b 88 ff ff ...6............ [521120.728822] Object ffff880f36b38710: 02 00 00 f0 00 00 00 00 00 00 00 00 00 00 00 00 ................ [521120.729705] Object ffff880f36b38720: 01 00 00 00 00 00 00 00 00 00 00 00 01 00 00 00 ................ [521120.730623] Object ffff880f36b38730: 00 00 00 00 00 00 00 00 01 00 00 00 00 02 00 00 ................ [521120.731621] Object ffff880f36b38740: 00 02 00 00 01 00 00 00 d0 f7 87 ad ff ff ff ff ................ [521120.732776] Object ffff880f36b38750: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 ................ [521120.733640] Object ffff880f36b38760: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 ................ [521120.734508] Object ffff880f36b38770: 01 00 03 00 01 00 00 00 88 87 b3 36 0f 88 ff ff ...........6.... [521120.735385] Object ffff880f36b38780: 00 73 22 ad 02 88 ff ff 40 13 e0 3c 00 ea ff ff .s".....@..<.... [521120.736667] Object ffff880f36b38790: 00 02 00 00 00 04 00 00 00 00 00 00 00 00 00 00 ................ [521120.737596] Object ffff880f36b387a0: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 ................ [521120.738524] Object ffff880f36b387b0: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 ................ [521120.739388] Object ffff880f36b387c0: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 ................ [521120.740277] Object ffff880f36b387d0: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 ................ [521120.741187] Object ffff880f36b387e0: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 ................ [521120.742233] Object ffff880f36b387f0: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 ................ [521120.743229] CPU: 41 PID: 9644 Comm: mount.ocfs2 Tainted: G B 4.2.0-rc6-next-20150810-sasha-00039-gf909086 #2420 [521120.744274] ffff880f36b38000 ffff880d89c8f638 ffffffffb6e9ba8a ffff880101c0e5c0 [521120.745025] ffff880d89c8f668 ffffffffad76a313 ffff880101c0e5c0 ffffea003cdace00 [521120.745908] ffff880f36b38700 ffff880f36b38798 ffff880d89c8f690 ffffffffad772854 [521120.747063] Call Trace: [521120.747520] dump_stack (lib/dump_stack.c:52) [521120.748053] print_trailer (mm/slub.c:653) [521120.748582] object_err (mm/slub.c:660) [521120.749079] kasan_report_error (include/linux/kasan.h:20 mm/kasan/report.c:152 mm/kasan/report.c:194) [521120.750834] __asan_report_load4_noabort (mm/kasan/report.c:250) [521120.753580] dio_bio_complete (fs/direct-io.c:478) [521120.755752] do_blockdev_direct_IO (fs/direct-io.c:494 fs/direct-io.c:1291) [521120.759765] __blockdev_direct_IO (fs/direct-io.c:1322) [521120.761658] blkdev_direct_IO (fs/block_dev.c:162) [521120.762993] generic_file_read_iter (mm/filemap.c:1738) [521120.767405] blkdev_read_iter (fs/block_dev.c:1649) [521120.768556] __vfs_read (fs/read_write.c:423 fs/read_write.c:434) [521120.772126] vfs_read (fs/read_write.c:454) [521120.773118] SyS_pread64 (fs/read_write.c:607 fs/read_write.c:594) [521120.776062] entry_SYSCALL_64_fastpath (arch/x86/entry/entry_64.S:186) [521120.777375] Memory state around the buggy address: [521120.778118] ffff880f36b38600: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb [521120.779211] ffff880f36b38680: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb [521120.780315] >ffff880f36b38700: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb [521120.781465] ^ [521120.782083] ffff880f36b38780: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb [521120.783717] ffff880f36b38800: fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc [521120.784818] ================================================================== This patch fixes a few of those places that I caught while auditing the patch, but the original patch should be audited further for more occurences of this issue since I'm not too familiar with the code. Signed-off-by: Sasha Levin Signed-off-by: Jens Axboe --- diff --git a/drivers/md/dm-crypt.c b/drivers/md/dm-crypt.c index 744b80c608e5..59da573cf994 100644 --- a/drivers/md/dm-crypt.c +++ b/drivers/md/dm-crypt.c @@ -1102,6 +1102,7 @@ static void crypt_endio(struct bio *clone) struct dm_crypt_io *io = clone->bi_private; struct crypt_config *cc = io->cc; unsigned rw = bio_data_dir(clone); + int error; /* * free the processed pages @@ -1109,15 +1110,16 @@ static void crypt_endio(struct bio *clone) if (rw == WRITE) crypt_free_buffer_pages(cc, clone); + error = clone->bi_error; bio_put(clone); - if (rw == READ && !clone->bi_error) { + if (rw == READ && !error) { kcryptd_queue_crypt(io); return; } - if (unlikely(clone->bi_error)) - io->error = clone->bi_error; + if (unlikely(error)) + io->error = error; crypt_dec_pending(io); } diff --git a/drivers/md/dm-io.c b/drivers/md/dm-io.c index efc6659f9d6a..c84714f70378 100644 --- a/drivers/md/dm-io.c +++ b/drivers/md/dm-io.c @@ -138,6 +138,7 @@ static void endio(struct bio *bio) { struct io *io; unsigned region; + int error; if (bio->bi_error && bio_data_dir(bio) == READ) zero_fill_bio(bio); @@ -147,9 +148,10 @@ static void endio(struct bio *bio) */ retrieve_io_and_region_from_bio(bio, &io, ®ion); + error = bio->bi_error; bio_put(bio); - dec_count(io, region, bio->bi_error); + dec_count(io, region, error); } /*----------------------------------------------------------------- diff --git a/drivers/md/raid5.c b/drivers/md/raid5.c index e3d48775c9df..085db931aafc 100644 --- a/drivers/md/raid5.c +++ b/drivers/md/raid5.c @@ -4756,6 +4756,7 @@ static void raid5_align_endio(struct bio *bi) struct mddev *mddev; struct r5conf *conf; struct md_rdev *rdev; + int error = bi->bi_error; bio_put(bi); @@ -4766,7 +4767,7 @@ static void raid5_align_endio(struct bio *bi) rdev_dec_pending(rdev, conf->mddev); - if (!bi->bi_error) { + if (!error) { trace_block_bio_complete(bdev_get_queue(raid_bi->bi_bdev), raid_bi, 0); bio_endio(raid_bi); diff --git a/fs/direct-io.c b/fs/direct-io.c index e1639c8c14d5..818c647f36d3 100644 --- a/fs/direct-io.c +++ b/fs/direct-io.c @@ -459,12 +459,14 @@ static int dio_bio_complete(struct dio *dio, struct bio *bio) { struct bio_vec *bvec; unsigned i; + int err; if (bio->bi_error) dio->io_error = -EIO; if (dio->is_async && dio->rw == READ) { bio_check_pages_dirty(bio); /* transfers ownership */ + err = bio->bi_error; } else { bio_for_each_segment_all(bvec, bio, i) { struct page *page = bvec->bv_page; @@ -473,9 +475,10 @@ static int dio_bio_complete(struct dio *dio, struct bio *bio) set_page_dirty_lock(page); page_cache_release(page); } + err = bio->bi_error; bio_put(bio); } - return bio->bi_error; + return err; } /*