The patch below does not apply to the 6.1-stable tree. If someone wants it applied there, or to any other stable or longterm tree, then please email the backport, including the original git commit id to stable@vger.kernel.org.

To reproduce the conflict and resubmit, you may use the following commands:

git fetch https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git/ linux-6.1.y git checkout FETCH_HEAD git cherry-pick -x 8e7860543a94784d744c7ce34b78a2e11beefa5c # <resolve conflicts, build, test, etc.> git commit -s git send-email --to 'stable@vger.kernel.org' --in-reply-to '2024072924-overact-drainable-8abb@gregkh' --subject-prefix 'PATCH 6.1.y' HEAD^..

Possible dependencies:

8e7860543a94 ("btrfs: fix extent map use-after-free when adding pages to compressed bio") b7d463a1d125 ("btrfs: store a pointer to the original btrfs_bio in struct compressed_bio") 690834e47cf7 ("btrfs: pass a btrfs_bio to btrfs_submit_compressed_read") 7edb9a3e7200 ("btrfs: move zero filling of compressed read bios into common code") 32586c5bca72 ("btrfs: factor out a btrfs_free_compressed_pages helper") 10e924bc320a ("btrfs: factor out a btrfs_add_compressed_bio_pages helper") d7294e4deeb9 ("btrfs: use the bbio file offset in add_ra_bio_pages") e7aff33e3161 ("btrfs: use the bbio file offset in btrfs_submit_compressed_read") 798c9fc74d03 ("btrfs: remove redundant free_extent_map in btrfs_submit_compressed_read") 544fe4a903ce ("btrfs: embed a btrfs_bio into struct compressed_bio") d5e4377d5051 ("btrfs: split zone append bios in btrfs_submit_bio") 35a8d7da3ca8 ("btrfs: remove now spurious bio submission helpers") 285599b6fe15 ("btrfs: remove the fs_info argument to btrfs_submit_bio") 48253076c3a9 ("btrfs: open code submit_encoded_read_bio") 30493ff49f81 ("btrfs: remove stripe boundary calculation for compressed I/O") 2380220e1e13 ("btrfs: remove stripe boundary calculation for buffered I/O") 67d669825090 ("btrfs: pass the iomap bio to btrfs_submit_bio") 852eee62d31a ("btrfs: allow btrfs_submit_bio to split bios") 69ccf3f4244a ("btrfs: handle recording of zoned writes in the storage layer") f8a53bb58ec7 ("btrfs: handle checksum generation in the storage layer")

thanks,

greg k-h

------------------ original commit in Linus's tree ------------------

From 8e7860543a94784d744c7ce34b78a2e11beefa5c Mon Sep 17 00:00:00 2001 From: Filipe Manana fdmanana@suse.com Date: Thu, 4 Jul 2024 16:11:20 +0100 Subject: [PATCH] btrfs: fix extent map use-after-free when adding pages to compressed bio

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

diff --git a/fs/btrfs/compression.c b/fs/btrfs/compression.c index a149f3659b15..a8e2c461aff7 100644 --- a/fs/btrfs/compression.c +++ b/fs/btrfs/compression.c @@ -515,6 +515,7 @@ static noinline int add_ra_bio_pages(struct inode *inode, put_page(page); break; } + add_size = min(em->start + em->len, page_end + 1) - cur; free_extent_map(em);

if (page->index == end_index) { @@ -527,7 +528,6 @@ static noinline int add_ra_bio_pages(struct inode *inode, } }

- add_size = min(em->start + em->len, page_end + 1) - cur; ret = bio_add_page(orig_bio, page, add_size, offset_in_page(cur)); if (ret != add_size) { unlock_extent(tree, cur, page_end, NULL);