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block: Split out bio_list_copy_data()

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Found a bug (with ASAN) where we were passing a bio to bio_copy_data()
with bi_next not NULL, when it should have been - a driver had left
bi_next set to something after calling bio_endio().

Since the normal case is only copying single bios, split out
bio_list_copy_data() to avoid more bugs like this in the future.

Signed-off-by: Kent Overstreet <kent.overstreet@gmail.com>
Signed-off-by: Jens Axboe <axboe@kernel.dk>
This commit is contained in:
Kent Overstreet 2018-05-08 21:33:54 -04:00 committed by Jens Axboe
parent 38a72dac48
commit 45db54d58d
3 changed files with 62 additions and 42 deletions
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97
block/bio.c
View File

@ -971,13 +971,67 @@ void bio_advance(struct bio *bio, unsigned bytes)
}
EXPORT_SYMBOL(bio_advance);
void bio_copy_data_iter(struct bio *dst, struct bvec_iter dst_iter,
struct bio *src, struct bvec_iter src_iter)
void bio_copy_data_iter(struct bio *dst, struct bvec_iter *dst_iter,
struct bio *src, struct bvec_iter *src_iter)
{
struct bio_vec src_bv, dst_bv;
void *src_p, *dst_p;
unsigned bytes;
while (src_iter->bi_size && dst_iter->bi_size) {
src_bv = bio_iter_iovec(src, *src_iter);
dst_bv = bio_iter_iovec(dst, *dst_iter);
bytes = min(src_bv.bv_len, dst_bv.bv_len);
src_p = kmap_atomic(src_bv.bv_page);
dst_p = kmap_atomic(dst_bv.bv_page);
memcpy(dst_p + dst_bv.bv_offset,
src_p + src_bv.bv_offset,
bytes);
kunmap_atomic(dst_p);
kunmap_atomic(src_p);
bio_advance_iter(src, src_iter, bytes);
bio_advance_iter(dst, dst_iter, bytes);
}
}
EXPORT_SYMBOL(bio_copy_data_iter);
/**
* bio_copy_data - copy contents of data buffers from one bio to another
* @src: source bio
* @dst: destination bio
*
* Stops when it reaches the end of either @src or @dst - that is, copies
* min(src->bi_size, dst->bi_size) bytes (or the equivalent for lists of bios).
*/
void bio_copy_data(struct bio *dst, struct bio *src)
{
struct bvec_iter src_iter = src->bi_iter;
struct bvec_iter dst_iter = dst->bi_iter;
bio_copy_data_iter(dst, &dst_iter, src, &src_iter);
}
EXPORT_SYMBOL(bio_copy_data);
/**
* bio_list_copy_data - copy contents of data buffers from one chain of bios to
* another
* @src: source bio list
* @dst: destination bio list
*
* Stops when it reaches the end of either the @src list or @dst list - that is,
* copies min(src->bi_size, dst->bi_size) bytes (or the equivalent for lists of
* bios).
*/
void bio_list_copy_data(struct bio *dst, struct bio *src)
{
struct bvec_iter src_iter = src->bi_iter;
struct bvec_iter dst_iter = dst->bi_iter;
while (1) {
if (!src_iter.bi_size) {
src = src->bi_next;
@ -995,45 +1049,10 @@ void bio_copy_data_iter(struct bio *dst, struct bvec_iter dst_iter,
dst_iter = dst->bi_iter;
}
src_bv = bio_iter_iovec(src, src_iter);
dst_bv = bio_iter_iovec(dst, dst_iter);
bytes = min(src_bv.bv_len, dst_bv.bv_len);
src_p = kmap_atomic(src_bv.bv_page);
dst_p = kmap_atomic(dst_bv.bv_page);
memcpy(dst_p + dst_bv.bv_offset,
src_p + src_bv.bv_offset,
bytes);
kunmap_atomic(dst_p);
kunmap_atomic(src_p);
bio_advance_iter(src, &src_iter, bytes);
bio_advance_iter(dst, &dst_iter, bytes);
bio_copy_data_iter(dst, &dst_iter, src, &src_iter);
}
}
EXPORT_SYMBOL(bio_copy_data_iter);
/**
* bio_copy_data - copy contents of data buffers from one chain of bios to
* another
* @src: source bio list
* @dst: destination bio list
*
* If @src and @dst are single bios, bi_next must be NULL - otherwise, treats
* @src and @dst as linked lists of bios.
*
* Stops when it reaches the end of either @src or @dst - that is, copies
* min(src->bi_size, dst->bi_size) bytes (or the equivalent for lists of bios).
*/
void bio_copy_data(struct bio *dst, struct bio *src)
{
bio_copy_data_iter(dst, dst->bi_iter,
src, src->bi_iter);
}
EXPORT_SYMBOL(bio_copy_data);
EXPORT_SYMBOL(bio_list_copy_data);
struct bio_map_data {
int is_our_pages;

2
drivers/block/pktcdvd.c
View File

@ -1285,7 +1285,7 @@ static void pkt_start_write(struct pktcdvd_device *pd, struct packet_data *pkt)
* Fill-in bvec with data from orig_bios.
*/
spin_lock(&pkt->lock);
bio_copy_data(pkt->w_bio, pkt->orig_bios.head);
bio_list_copy_data(pkt->w_bio, pkt->orig_bios.head);
pkt_set_state(pkt, PACKET_WRITE_WAIT_STATE);
spin_unlock(&pkt->lock);

5
include/linux/bio.h
View File

@ -505,9 +505,10 @@ static inline void bio_flush_dcache_pages(struct bio *bi)
}
#endif
extern void bio_copy_data_iter(struct bio *dst, struct bvec_iter dst_iter,
struct bio *src, struct bvec_iter src_iter);
extern void bio_copy_data_iter(struct bio *dst, struct bvec_iter *dst_iter,
struct bio *src, struct bvec_iter *src_iter);
extern void bio_copy_data(struct bio *dst, struct bio *src);
extern void bio_list_copy_data(struct bio *dst, struct bio *src);
extern void bio_free_pages(struct bio *bio);
extern struct bio *bio_copy_user_iov(struct request_queue *,