[dm-devel] [PATCH] block: don't access bio->bi_error after bio_put()
Sasha Levin
sasha.levin at oracle.com
Mon Aug 10 23:05:18 UTC 2015
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"..... at ..<....
[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 <sasha.levin at oracle.com>
---
drivers/md/dm-crypt.c | 8 +++++---
drivers/md/dm-io.c | 4 +++-
drivers/md/raid5.c | 3 ++-
fs/direct-io.c | 5 ++++-
4 files changed, 14 insertions(+), 6 deletions(-)
diff --git a/drivers/md/dm-crypt.c b/drivers/md/dm-crypt.c
index 744b80c..59da573 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 efc6659..c84714f7 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 358deaf..394f5fc 100644
--- a/drivers/md/raid5.c
+++ b/drivers/md/raid5.c
@@ -4763,6 +4763,7 @@ 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);
@@ -4773,7 +4774,7 @@ 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 e1639c8..818c647 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;
}
/*
--
1.7.10.4
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