From dff4f9ff5d7f289e4545cc936362e01ed3252742 Mon Sep 17 00:00:00 2001 From: Anderson Nascimento Date: Mon, 8 Sep 2025 09:49:02 -0300 Subject: [PATCH 1/2] btrfs: avoid potential out-of-bounds in btrfs_encode_fh() The function btrfs_encode_fh() does not properly account for the three cases it handles. Before writing to the file handle (fh), the function only returns to the user BTRFS_FID_SIZE_NON_CONNECTABLE (5 dwords, 20 bytes) or BTRFS_FID_SIZE_CONNECTABLE (8 dwords, 32 bytes). However, when a parent exists and the root ID of the parent and the inode are different, the function writes BTRFS_FID_SIZE_CONNECTABLE_ROOT (10 dwords, 40 bytes). If *max_len is not large enough, this write goes out of bounds because BTRFS_FID_SIZE_CONNECTABLE_ROOT is greater than BTRFS_FID_SIZE_CONNECTABLE originally returned. This results in an 8-byte out-of-bounds write at fid->parent_root_objectid = parent_root_id. A previous attempt to fix this issue was made but was lost. https://lore.kernel.org/all/4CADAEEC020000780001B32C@vpn.id2.novell.com/ Although this issue does not seem to be easily triggerable, it is a potential memory corruption bug that should be fixed. This patch resolves the issue by ensuring the function returns the appropriate size for all three cases and validates that *max_len is large enough before writing any data. Fixes: be6e8dc0ba84 ("NFS support for btrfs - v3") CC: stable@vger.kernel.org # 3.0+ Signed-off-by: Anderson Nascimento Reviewed-by: David Sterba Signed-off-by: David Sterba --- fs/btrfs/export.c | 8 +++++++- 1 file changed, 7 insertions(+), 1 deletion(-) diff --git a/fs/btrfs/export.c b/fs/btrfs/export.c index d062ac521051..230d9326b685 100644 --- a/fs/btrfs/export.c +++ b/fs/btrfs/export.c @@ -23,7 +23,11 @@ static int btrfs_encode_fh(struct inode *inode, u32 *fh, int *max_len, int type; if (parent && (len < BTRFS_FID_SIZE_CONNECTABLE)) { - *max_len = BTRFS_FID_SIZE_CONNECTABLE; + if (btrfs_root_id(BTRFS_I(inode)->root) != + btrfs_root_id(BTRFS_I(parent)->root)) + *max_len = BTRFS_FID_SIZE_CONNECTABLE_ROOT; + else + *max_len = BTRFS_FID_SIZE_CONNECTABLE; return FILEID_INVALID; } else if (len < BTRFS_FID_SIZE_NON_CONNECTABLE) { *max_len = BTRFS_FID_SIZE_NON_CONNECTABLE; @@ -45,6 +49,8 @@ static int btrfs_encode_fh(struct inode *inode, u32 *fh, int *max_len, parent_root_id = btrfs_root_id(BTRFS_I(parent)->root); if (parent_root_id != fid->root_objectid) { + if (*max_len < BTRFS_FID_SIZE_CONNECTABLE_ROOT) + return FILEID_INVALID; fid->parent_root_objectid = parent_root_id; len = BTRFS_FID_SIZE_CONNECTABLE_ROOT; type = FILEID_BTRFS_WITH_PARENT_ROOT; From 4335c4496b1bcf8e85761af23550a180e937bac6 Mon Sep 17 00:00:00 2001 From: Nathan Chancellor Date: Thu, 25 Sep 2025 19:03:04 -0400 Subject: [PATCH 2/2] btrfs: fix PAGE_SIZE format specifier in open_ctree() There is an instance of -Wformat when targeting 32-bit architectures due to using a 'size_t' specifier (which is 'unsigned int' for 32-bit platforms) to print PAGE_SIZE: In file included from fs/btrfs/compression.h:17, from fs/btrfs/extent_io.h:15, from fs/btrfs/locking.h:13, from fs/btrfs/ctree.h:19, from fs/btrfs/disk-io.c:22: fs/btrfs/disk-io.c: In function 'open_ctree': include/linux/kern_levels.h:5:25: error: format '%zu' expects argument of type 'size_t', but argument 4 has type 'long unsigned int' [-Werror=format=] ... fs/btrfs/disk-io.c:3398:17: note: in expansion of macro 'btrfs_warn' 3398 | btrfs_warn(fs_info, | ^~~~~~~~~~ PAGE_SIZE is consistently defined as an 'unsigned long' in include/vsdo/page.h so use '%lu' to clear up the warning. Fixes: 98077f7f2180 ("btrfs: enable experimental bs > ps support") Reviewed-by: Qu Wenruo Tested-by: Geert Uytterhoeven Signed-off-by: Nathan Chancellor Reviewed-by: David Sterba Signed-off-by: David Sterba --- fs/btrfs/disk-io.c | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-) diff --git a/fs/btrfs/disk-io.c b/fs/btrfs/disk-io.c index 21c2a19d690f..f475fb2272ac 100644 --- a/fs/btrfs/disk-io.c +++ b/fs/btrfs/disk-io.c @@ -3396,7 +3396,7 @@ int __cold open_ctree(struct super_block *sb, struct btrfs_fs_devices *fs_device if (fs_info->sectorsize > PAGE_SIZE) btrfs_warn(fs_info, - "support for block size %u with page size %zu is experimental, some features may be missing", + "support for block size %u with page size %lu is experimental, some features may be missing", fs_info->sectorsize, PAGE_SIZE); /* * Handle the space caching options appropriately now that we have the