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@xxxxxxxxxxxxxxx>. 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 95c8e349d8e8f190e28854e7ca96de866d2dc5a4 # <resolve conflicts, build, test, etc.> git commit -s git send-email --to '<stable@xxxxxxxxxxxxxxx>' --in-reply-to '2023071644-boxer-satchel-5beb@gregkh' --subject-prefix 'PATCH 6.1.y' HEAD^.. Possible dependencies: 95c8e349d8e8 ("btrfs: warn on invalid slot in tree mod log rewind") e23efd8e8767 ("btrfs: add eb to btrfs_node_key_ptr_offset") 07e81dc94474 ("btrfs: move accessor helpers into accessors.h") ad1ac5012c2b ("btrfs: move btrfs_map_token to accessors") 55e5cfd36da5 ("btrfs: remove fs_info::pending_changes and related code") 7966a6b5959b ("btrfs: move fs_info::flags enum to fs.h") fc97a410bd78 ("btrfs: move mount option definitions to fs.h") 0d3a9cf8c306 ("btrfs: convert incompat and compat flag test helpers to macros") ec8eb376e271 ("btrfs: move BTRFS_FS_STATE* definitions and helpers to fs.h") 9b569ea0be6f ("btrfs: move the printk helpers out of ctree.h") e118578a8df7 ("btrfs: move assert helpers out of ctree.h") c7f13d428ea1 ("btrfs: move fs wide helpers out of ctree.h") 63a7cb130718 ("btrfs: auto enable discard=async when possible") 7a66eda351ba ("btrfs: move the btrfs_verity_descriptor_item defs up in ctree.h") 956504a331a6 ("btrfs: move trans_handle_cachep out of ctree.h") f1e5c6185ca1 ("btrfs: move flush related definitions to space-info.h") ed4c491a3db2 ("btrfs: move BTRFS_MAX_MIRRORS into scrub.c") 4300c58f8090 ("btrfs: move btrfs on-disk definitions out of ctree.h") d60d956eb41f ("btrfs: remove unused set/clear_pending_info helpers") thanks, greg k-h ------------------ original commit in Linus's tree ------------------ >From 95c8e349d8e8f190e28854e7ca96de866d2dc5a4 Mon Sep 17 00:00:00 2001 From: Boris Burkov <boris@xxxxxx> Date: Thu, 1 Jun 2023 11:55:13 -0700 Subject: [PATCH] btrfs: warn on invalid slot in tree mod log rewind The way that tree mod log tracks the ultimate length of the eb, the variable 'n', eventually turns up the correct value, but at intermediate steps during the rewind, n can be inaccurate as a representation of the end of the eb. For example, it doesn't get updated on move rewinds, and it does get updated for add/remove in the middle of the eb. To detect cases with invalid moves, introduce a separate variable called max_slot which tries to track the maximum valid slot in the rewind eb. We can then warn if we do a move whose src range goes beyond the max valid slot. There is a commented caveat that it is possible to have this value be an overestimate due to the challenge of properly handling 'add' operations in the middle of the eb, but in practice it doesn't cause enough of a problem to throw out the max idea in favor of tracking every valid slot. CC: stable@xxxxxxxxxxxxxxx # 5.15+ Reviewed-by: Filipe Manana <fdmanana@xxxxxxxx> Signed-off-by: Boris Burkov <boris@xxxxxx> Signed-off-by: David Sterba <dsterba@xxxxxxxx> diff --git a/fs/btrfs/tree-mod-log.c b/fs/btrfs/tree-mod-log.c index a555baa0143a..39545d1d2e9a 100644 --- a/fs/btrfs/tree-mod-log.c +++ b/fs/btrfs/tree-mod-log.c @@ -664,10 +664,27 @@ static void tree_mod_log_rewind(struct btrfs_fs_info *fs_info, unsigned long o_dst; unsigned long o_src; unsigned long p_size = sizeof(struct btrfs_key_ptr); + /* + * max_slot tracks the maximum valid slot of the rewind eb at every + * step of the rewind. This is in contrast with 'n' which eventually + * matches the number of items, but can be wrong during moves or if + * removes overlap on already valid slots (which is probably separately + * a bug). We do this to validate the offsets of memmoves for rewinding + * moves and detect invalid memmoves. + * + * Since a rewind eb can start empty, max_slot is a signed integer with + * a special meaning for -1, which is that no slot is valid to move out + * of. Any other negative value is invalid. + */ + int max_slot; + int move_src_end_slot; + int move_dst_end_slot; n = btrfs_header_nritems(eb); + max_slot = n - 1; read_lock(&fs_info->tree_mod_log_lock); while (tm && tm->seq >= time_seq) { + ASSERT(max_slot >= -1); /* * All the operations are recorded with the operator used for * the modification. As we're going backwards, we do the @@ -684,6 +701,8 @@ static void tree_mod_log_rewind(struct btrfs_fs_info *fs_info, btrfs_set_node_ptr_generation(eb, tm->slot, tm->generation); n++; + if (tm->slot > max_slot) + max_slot = tm->slot; break; case BTRFS_MOD_LOG_KEY_REPLACE: BUG_ON(tm->slot >= n); @@ -693,14 +712,37 @@ static void tree_mod_log_rewind(struct btrfs_fs_info *fs_info, tm->generation); break; case BTRFS_MOD_LOG_KEY_ADD: + /* + * It is possible we could have already removed keys + * behind the known max slot, so this will be an + * overestimate. In practice, the copy operation + * inserts them in increasing order, and overestimating + * just means we miss some warnings, so it's OK. It + * isn't worth carefully tracking the full array of + * valid slots to check against when moving. + */ + if (tm->slot == max_slot) + max_slot--; /* if a move operation is needed it's in the log */ n--; break; case BTRFS_MOD_LOG_MOVE_KEYS: + ASSERT(tm->move.nr_items > 0); + move_src_end_slot = tm->move.dst_slot + tm->move.nr_items - 1; + move_dst_end_slot = tm->slot + tm->move.nr_items - 1; o_dst = btrfs_node_key_ptr_offset(eb, tm->slot); o_src = btrfs_node_key_ptr_offset(eb, tm->move.dst_slot); + if (WARN_ON(move_src_end_slot > max_slot || + tm->move.nr_items <= 0)) { + btrfs_warn(fs_info, +"move from invalid tree mod log slot eb %llu slot %d dst_slot %d nr_items %d seq %llu n %u max_slot %d", + eb->start, tm->slot, + tm->move.dst_slot, tm->move.nr_items, + tm->seq, n, max_slot); + } memmove_extent_buffer(eb, o_dst, o_src, tm->move.nr_items * p_size); + max_slot = move_dst_end_slot; break; case BTRFS_MOD_LOG_ROOT_REPLACE: /*
