Commit e04ca626 authored by Chris Mason's avatar Chris Mason
Browse files

Btrfs: Fix use after free during compressed reads



Yan's fix to use the correct file offset during compressed reads used the
extent_map struct pointer after it had been freed.  This saves the
fields we want for later use instead.
Signed-off-by: default avatarChris Mason <chris.mason@oracle.com>
parent ff5b7ee3
......@@ -505,6 +505,8 @@ int btrfs_submit_compressed_read(struct inode *inode, struct bio *bio,
struct block_device *bdev;
struct bio *comp_bio;
u64 cur_disk_byte = (u64)bio->bi_sector << 9;
u64 em_len;
u64 em_start;
struct extent_map *em;
int ret;
......@@ -525,7 +527,10 @@ int btrfs_submit_compressed_read(struct inode *inode, struct bio *bio,
cb->start = em->orig_start;
compressed_len = em->block_len;
em_len = em->len;
em_start = em->start;
free_extent_map(em);
em = NULL;
cb->len = uncompressed_len;
cb->compressed_len = compressed_len;
......@@ -543,7 +548,7 @@ int btrfs_submit_compressed_read(struct inode *inode, struct bio *bio,
}
cb->nr_pages = nr_pages;
add_ra_bio_pages(inode, em->start + em->len, cb);
add_ra_bio_pages(inode, em_start + em_len, cb);
if (!btrfs_test_opt(root, NODATASUM) &&
!btrfs_test_flag(inode, NODATASUM)) {
......
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