6.1-stable review patch. If anyone has any objections, please let me know.
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From: Filipe Manana fdmanana@suse.com
commit 8e7860543a94784d744c7ce34b78a2e11beefa5c upstream.
At add_ra_bio_pages() we are accessing the extent map to calculate 'add_size' after we dropped our reference on the extent map, resulting in a use-after-free. Fix this by computing 'add_size' before dropping our extent map reference.
Reported-by: syzbot+853d80cba98ce1157ae6@syzkaller.appspotmail.com Link: https://lore.kernel.org/linux-btrfs/000000000000038144061c6d18f2@google.com/ Fixes: 6a4049102055 ("btrfs: subpage: make add_ra_bio_pages() compatible") CC: stable@vger.kernel.org # 6.1+ Signed-off-by: Filipe Manana fdmanana@suse.com Reviewed-by: David Sterba dsterba@suse.com Signed-off-by: David Sterba dsterba@suse.com Signed-off-by: Brennan Lamoreaux brennan.lamoreaux@broadcom.com Signed-off-by: Greg Kroah-Hartman gregkh@linuxfoundation.org --- fs/btrfs/compression.c | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-)
--- a/fs/btrfs/compression.c +++ b/fs/btrfs/compression.c @@ -613,6 +613,7 @@ static noinline int add_ra_bio_pages(str put_page(page); break; } + add_size = min(em->start + em->len, page_end + 1) - cur; free_extent_map(em);
if (page->index == end_index) { @@ -625,7 +626,6 @@ static noinline int add_ra_bio_pages(str } }
- add_size = min(em->start + em->len, page_end + 1) - cur; ret = bio_add_page(cb->orig_bio, page, add_size, offset_in_page(cur)); if (ret != add_size) { unlock_extent(tree, cur, page_end, NULL);