From 6f9a8ab796c6528d22de3c504c81fce7dde63d8a Mon Sep 17 00:00:00 2001 From: Kees Cook Date: Fri, 25 Apr 2025 23:23:29 -0700 Subject: [PATCH 1/6] btrfs: compression: adjust cb->compressed_folios allocation type In preparation for making the kmalloc() family of allocators type aware, we need to make sure that the returned type from the allocation matches the type of the variable being assigned. (Before, the allocator would always return "void *", which can be implicitly cast to any pointer type.) The assigned type is "struct folio **" but the returned type will be "struct page **". These are the same allocation size (pointer size), but the types don't match. Adjust the allocation type to match the assignment. Reviewed-by: Qu Wenruo Signed-off-by: Kees Cook Reviewed-by: David Sterba Signed-off-by: David Sterba --- fs/btrfs/compression.c | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-) diff --git a/fs/btrfs/compression.c b/fs/btrfs/compression.c index e7f8ee5d48a4..7f11ef559be6 100644 --- a/fs/btrfs/compression.c +++ b/fs/btrfs/compression.c @@ -606,7 +606,7 @@ void btrfs_submit_compressed_read(struct btrfs_bio *bbio) free_extent_map(em); cb->nr_folios = DIV_ROUND_UP(compressed_len, PAGE_SIZE); - cb->compressed_folios = kcalloc(cb->nr_folios, sizeof(struct page *), GFP_NOFS); + cb->compressed_folios = kcalloc(cb->nr_folios, sizeof(struct folio *), GFP_NOFS); if (!cb->compressed_folios) { ret = BLK_STS_RESOURCE; goto out_free_bio; From bc7e0975093567f51be8e1bdf4aa5900a3cf0b1e Mon Sep 17 00:00:00 2001 From: Goldwyn Rodrigues Date: Fri, 25 Apr 2025 09:25:06 -0400 Subject: [PATCH 2/6] btrfs: correct the order of prelim_ref arguments in btrfs__prelim_ref btrfs_prelim_ref() calls the old and new reference variables in the incorrect order. This causes a NULL pointer dereference because oldref is passed as NULL to trace_btrfs_prelim_ref_insert(). Note, trace_btrfs_prelim_ref_insert() is being called with newref as oldref (and oldref as NULL) on purpose in order to print out the values of newref. To reproduce: echo 1 > /sys/kernel/debug/tracing/events/btrfs/btrfs_prelim_ref_insert/enable Perform some writeback operations. Backtrace: BUG: kernel NULL pointer dereference, address: 0000000000000018 #PF: supervisor read access in kernel mode #PF: error_code(0x0000) - not-present page PGD 115949067 P4D 115949067 PUD 11594a067 PMD 0 Oops: Oops: 0000 [#1] SMP NOPTI CPU: 1 UID: 0 PID: 1188 Comm: fsstress Not tainted 6.15.0-rc2-tester+ #47 PREEMPT(voluntary) 7ca2cef72d5e9c600f0c7718adb6462de8149622 Hardware name: QEMU Standard PC (Q35 + ICH9, 2009), BIOS rel-1.16.3-2-gc13ff2cd-prebuilt.qemu.org 04/01/2014 RIP: 0010:trace_event_raw_event_btrfs__prelim_ref+0x72/0x130 Code: e8 43 81 9f ff 48 85 c0 74 78 4d 85 e4 0f 84 8f 00 00 00 49 8b 94 24 c0 06 00 00 48 8b 0a 48 89 48 08 48 8b 52 08 48 89 50 10 <49> 8b 55 18 48 89 50 18 49 8b 55 20 48 89 50 20 41 0f b6 55 28 88 RSP: 0018:ffffce44820077a0 EFLAGS: 00010286 RAX: ffff8c6b403f9014 RBX: ffff8c6b55825730 RCX: 304994edf9cf506b RDX: d8b11eb7f0fdb699 RSI: ffff8c6b403f9010 RDI: ffff8c6b403f9010 RBP: 0000000000000001 R08: 0000000000000001 R09: 0000000000000010 R10: 00000000ffffffff R11: 0000000000000000 R12: ffff8c6b4e8fb000 R13: 0000000000000000 R14: ffffce44820077a8 R15: ffff8c6b4abd1540 FS: 00007f4dc6813740(0000) GS:ffff8c6c1d378000(0000) knlGS:0000000000000000 CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033 CR2: 0000000000000018 CR3: 000000010eb42000 CR4: 0000000000750ef0 PKRU: 55555554 Call Trace: prelim_ref_insert+0x1c1/0x270 find_parent_nodes+0x12a6/0x1ee0 ? __entry_text_end+0x101f06/0x101f09 ? srso_alias_return_thunk+0x5/0xfbef5 ? srso_alias_return_thunk+0x5/0xfbef5 ? srso_alias_return_thunk+0x5/0xfbef5 ? srso_alias_return_thunk+0x5/0xfbef5 btrfs_is_data_extent_shared+0x167/0x640 ? fiemap_process_hole+0xd0/0x2c0 extent_fiemap+0xa5c/0xbc0 ? __entry_text_end+0x101f05/0x101f09 btrfs_fiemap+0x7e/0xd0 do_vfs_ioctl+0x425/0x9d0 __x64_sys_ioctl+0x75/0xc0 Signed-off-by: Goldwyn Rodrigues Signed-off-by: David Sterba --- include/trace/events/btrfs.h | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-) diff --git a/include/trace/events/btrfs.h b/include/trace/events/btrfs.h index 549ab3b41961..3efc00cc1bcd 100644 --- a/include/trace/events/btrfs.h +++ b/include/trace/events/btrfs.h @@ -1928,7 +1928,7 @@ DECLARE_EVENT_CLASS(btrfs__prelim_ref, TP_PROTO(const struct btrfs_fs_info *fs_info, const struct prelim_ref *oldref, const struct prelim_ref *newref, u64 tree_size), - TP_ARGS(fs_info, newref, oldref, tree_size), + TP_ARGS(fs_info, oldref, newref, tree_size), TP_STRUCT__entry_btrfs( __field( u64, root_id ) From d6fe0c69b3aa5c985380b794bdf8e6e9b1811e60 Mon Sep 17 00:00:00 2001 From: Boris Burkov Date: Fri, 25 Apr 2025 12:47:50 -0700 Subject: [PATCH 3/6] btrfs: handle empty eb->folios in num_extent_folios() num_extent_folios() unconditionally calls folio_order() on eb->folios[0]. If that is NULL this will be a segfault. It is reasonable for it to return 0 as the number of folios in the eb when the first entry is NULL, so do that instead. Reviewed-by: Qu Wenruo Signed-off-by: Boris Burkov Reviewed-by: David Sterba Signed-off-by: David Sterba --- fs/btrfs/extent_io.h | 2 ++ 1 file changed, 2 insertions(+) diff --git a/fs/btrfs/extent_io.h b/fs/btrfs/extent_io.h index 2e261892c7bc..f5b28b5c4908 100644 --- a/fs/btrfs/extent_io.h +++ b/fs/btrfs/extent_io.h @@ -298,6 +298,8 @@ static inline int __pure num_extent_pages(const struct extent_buffer *eb) */ static inline int __pure num_extent_folios(const struct extent_buffer *eb) { + if (!eb->folios[0]) + return 0; if (folio_order(eb->folios[0])) return 1; return num_extent_pages(eb); From f95d186255b319c48a365d47b69bd997fecb674e Mon Sep 17 00:00:00 2001 From: Qu Wenruo Date: Tue, 29 Apr 2025 15:17:50 +0930 Subject: [PATCH 4/6] btrfs: avoid NULL pointer dereference if no valid csum tree [BUG] When trying read-only scrub on a btrfs with rescue=idatacsums mount option, it will crash with the following call trace: BUG: kernel NULL pointer dereference, address: 0000000000000208 #PF: supervisor read access in kernel mode #PF: error_code(0x0000) - not-present page CPU: 1 UID: 0 PID: 835 Comm: btrfs Tainted: G O 6.15.0-rc3-custom+ #236 PREEMPT(full) Hardware name: QEMU Standard PC (Q35 + ICH9, 2009), BIOS unknown 02/02/2022 RIP: 0010:btrfs_lookup_csums_bitmap+0x49/0x480 [btrfs] Call Trace: scrub_find_fill_first_stripe+0x35b/0x3d0 [btrfs] scrub_simple_mirror+0x175/0x290 [btrfs] scrub_stripe+0x5f7/0x6f0 [btrfs] scrub_chunk+0x9a/0x150 [btrfs] scrub_enumerate_chunks+0x333/0x660 [btrfs] btrfs_scrub_dev+0x23e/0x600 [btrfs] btrfs_ioctl+0x1dcf/0x2f80 [btrfs] __x64_sys_ioctl+0x97/0xc0 do_syscall_64+0x4f/0x120 entry_SYSCALL_64_after_hwframe+0x76/0x7e [CAUSE] Mount option "rescue=idatacsums" will completely skip loading the csum tree, so that any data read will not find any data csum thus we will ignore data checksum verification. Normally call sites utilizing csum tree will check the fs state flag NO_DATA_CSUMS bit, but unfortunately scrub does not check that bit at all. This results in scrub to call btrfs_search_slot() on a NULL pointer and triggered above crash. [FIX] Check both extent and csum tree root before doing any tree search. Reviewed-by: Johannes Thumshirn Signed-off-by: Qu Wenruo Reviewed-by: David Sterba Signed-off-by: David Sterba --- fs/btrfs/scrub.c | 4 ++-- 1 file changed, 2 insertions(+), 2 deletions(-) diff --git a/fs/btrfs/scrub.c b/fs/btrfs/scrub.c index 2c5edcee9450..c3b2e29e3e01 100644 --- a/fs/btrfs/scrub.c +++ b/fs/btrfs/scrub.c @@ -1541,8 +1541,8 @@ static int scrub_find_fill_first_stripe(struct btrfs_block_group *bg, u64 extent_gen; int ret; - if (unlikely(!extent_root)) { - btrfs_err(fs_info, "no valid extent root for scrub"); + if (unlikely(!extent_root || !csum_root)) { + btrfs_err(fs_info, "no valid extent or csum root for scrub"); return -EUCLEAN; } memset(stripe->sectors, 0, sizeof(struct scrub_sector_verification) * From 8fb1dcbbcc1ffe6ed7cf3f0f96d2737491dd1fbf Mon Sep 17 00:00:00 2001 From: Qu Wenruo Date: Fri, 17 Jan 2025 09:09:34 +1030 Subject: [PATCH 5/6] Revert "btrfs: canonicalize the device path before adding it" This reverts commit 7e06de7c83a746e58d4701e013182af133395188. Commit 7e06de7c83a7 ("btrfs: canonicalize the device path before adding it") tries to make btrfs to use "/dev/mapper/*" name first, then any filename inside "/dev/" as the device path. This is mostly fine when there is only the root namespace involved, but when multiple namespace are involved, things can easily go wrong for the d_path() usage. As d_path() returns a file path that is namespace dependent, the resulted string may not make any sense in another namespace. Furthermore, the "/dev/" prefix checks itself is not reliable, one can still make a valid initramfs without devtmpfs, and fill all needed device nodes manually. Overall the userspace has all its might to pass whatever device path for mount, and we are not going to win the war trying to cover every corner case. So just revert that commit, and do no extra d_path() based file path sanity check. CC: stable@vger.kernel.org # 6.12+ Link: https://lore.kernel.org/linux-fsdevel/20250115185608.GA2223535@zen.localdomain/ Reviewed-by: Boris Burkov Signed-off-by: Qu Wenruo Signed-off-by: David Sterba --- fs/btrfs/volumes.c | 91 +--------------------------------------------- 1 file changed, 1 insertion(+), 90 deletions(-) diff --git a/fs/btrfs/volumes.c b/fs/btrfs/volumes.c index c8c21c55be53..8e6b6fed7429 100644 --- a/fs/btrfs/volumes.c +++ b/fs/btrfs/volumes.c @@ -733,82 +733,6 @@ const u8 *btrfs_sb_fsid_ptr(const struct btrfs_super_block *sb) return has_metadata_uuid ? sb->metadata_uuid : sb->fsid; } -/* - * We can have very weird soft links passed in. - * One example is "/proc/self/fd/", which can be a soft link to - * a block device. - * - * But it's never a good idea to use those weird names. - * Here we check if the path (not following symlinks) is a good one inside - * "/dev/". - */ -static bool is_good_dev_path(const char *dev_path) -{ - struct path path = { .mnt = NULL, .dentry = NULL }; - char *path_buf = NULL; - char *resolved_path; - bool is_good = false; - int ret; - - if (!dev_path) - goto out; - - path_buf = kmalloc(PATH_MAX, GFP_KERNEL); - if (!path_buf) - goto out; - - /* - * Do not follow soft link, just check if the original path is inside - * "/dev/". - */ - ret = kern_path(dev_path, 0, &path); - if (ret) - goto out; - resolved_path = d_path(&path, path_buf, PATH_MAX); - if (IS_ERR(resolved_path)) - goto out; - if (strncmp(resolved_path, "/dev/", strlen("/dev/"))) - goto out; - is_good = true; -out: - kfree(path_buf); - path_put(&path); - return is_good; -} - -static int get_canonical_dev_path(const char *dev_path, char *canonical) -{ - struct path path = { .mnt = NULL, .dentry = NULL }; - char *path_buf = NULL; - char *resolved_path; - int ret; - - if (!dev_path) { - ret = -EINVAL; - goto out; - } - - path_buf = kmalloc(PATH_MAX, GFP_KERNEL); - if (!path_buf) { - ret = -ENOMEM; - goto out; - } - - ret = kern_path(dev_path, LOOKUP_FOLLOW, &path); - if (ret) - goto out; - resolved_path = d_path(&path, path_buf, PATH_MAX); - if (IS_ERR(resolved_path)) { - ret = PTR_ERR(resolved_path); - goto out; - } - ret = strscpy(canonical, resolved_path, PATH_MAX); -out: - kfree(path_buf); - path_put(&path); - return ret; -} - static bool is_same_device(struct btrfs_device *device, const char *new_path) { struct path old = { .mnt = NULL, .dentry = NULL }; @@ -1513,23 +1437,12 @@ struct btrfs_device *btrfs_scan_one_device(const char *path, blk_mode_t flags, bool new_device_added = false; struct btrfs_device *device = NULL; struct file *bdev_file; - char *canonical_path = NULL; u64 bytenr; dev_t devt; int ret; lockdep_assert_held(&uuid_mutex); - if (!is_good_dev_path(path)) { - canonical_path = kmalloc(PATH_MAX, GFP_KERNEL); - if (canonical_path) { - ret = get_canonical_dev_path(path, canonical_path); - if (ret < 0) { - kfree(canonical_path); - canonical_path = NULL; - } - } - } /* * Avoid an exclusive open here, as the systemd-udev may initiate the * device scan which may race with the user's mount or mkfs command, @@ -1574,8 +1487,7 @@ struct btrfs_device *btrfs_scan_one_device(const char *path, blk_mode_t flags, goto free_disk_super; } - device = device_list_add(canonical_path ? : path, disk_super, - &new_device_added); + device = device_list_add(path, disk_super, &new_device_added); if (!IS_ERR(device) && new_device_added) btrfs_free_stale_devices(device->devt, device); @@ -1584,7 +1496,6 @@ struct btrfs_device *btrfs_scan_one_device(const char *path, blk_mode_t flags, error_bdev_put: fput(bdev_file); - kfree(canonical_path); return device; } From 38e541051e1d19e8b1479a6af587a7884653e041 Mon Sep 17 00:00:00 2001 From: Kairui Song Date: Thu, 1 May 2025 02:10:48 +0800 Subject: [PATCH 6/6] btrfs: open code folio_index() in btree_clear_folio_dirty_tag() The folio_index() helper is only needed for mixed usage of page cache and swap cache, for pure page cache usage, the caller can just use folio->index instead. It can't be a swap cache folio here. Swap mapping may only call into fs through 'swap_rw' but btrfs does not use that method for swap. Reviewed-by: Matthew Wilcox (Oracle) Reviewed-by: Qu Wenruo Signed-off-by: Kairui Song Reviewed-by: David Sterba Signed-off-by: David Sterba --- fs/btrfs/extent_io.c | 4 ++-- 1 file changed, 2 insertions(+), 2 deletions(-) diff --git a/fs/btrfs/extent_io.c b/fs/btrfs/extent_io.c index 8515c31f563b..13bdd60da3c7 100644 --- a/fs/btrfs/extent_io.c +++ b/fs/btrfs/extent_io.c @@ -3508,8 +3508,8 @@ static void btree_clear_folio_dirty_tag(struct folio *folio) ASSERT(folio_test_locked(folio)); xa_lock_irq(&folio->mapping->i_pages); if (!folio_test_dirty(folio)) - __xa_clear_mark(&folio->mapping->i_pages, - folio_index(folio), PAGECACHE_TAG_DIRTY); + __xa_clear_mark(&folio->mapping->i_pages, folio->index, + PAGECACHE_TAG_DIRTY); xa_unlock_irq(&folio->mapping->i_pages); }