From 11e1cffb7e2492ddac4ab8d19ce466783adbb957 Mon Sep 17 00:00:00 2001 From: Darren Kenny Date: Tue, 29 Mar 2022 10:49:56 +0000 Subject: [PATCH 3/5] fs/btrfs: Fix several fuzz issues with invalid dir item sizing According to the btrfs code in Linux, the structure of a directory item leaf should be of the form: |struct btrfs_dir_item|name|data| in GRUB the name len and data len are in the grub_btrfs_dir_item structure's n and m fields respectively. The combined size of the structure, name and data should be less than the allocated memory, a difference to the Linux kernel's struct btrfs_dir_item is that the grub_btrfs_dir_item has an extra field for where the name is stored, so we adjust for that too. Signed-off-by: Darren Kenny Reviewed-by: Daniel Kiper --- grub-core/fs/btrfs.c | 26 ++++++++++++++++++++++++++ 1 file changed, 26 insertions(+) diff --git a/grub-core/fs/btrfs.c b/grub-core/fs/btrfs.c index 937153306..139c6616d 100644 --- a/grub-core/fs/btrfs.c +++ b/grub-core/fs/btrfs.c @@ -1991,6 +1991,7 @@ grub_btrfs_dir (grub_device_t device, const char *path, int r = 0; grub_uint64_t tree; grub_uint8_t type; + grub_size_t est_size = 0; if (!data) return grub_errno; @@ -2049,6 +2050,18 @@ grub_btrfs_dir (grub_device_t device, const char *path, break; } + if (direl == NULL || + grub_add (grub_le_to_cpu16 (direl->n), + grub_le_to_cpu16 (direl->m), &est_size) || + grub_add (est_size, sizeof (*direl), &est_size) || + grub_sub (est_size, sizeof (direl->name), &est_size) || + est_size > allocated) + { + grub_errno = GRUB_ERR_OUT_OF_RANGE; + r = -grub_errno; + goto out; + } + for (cdirel = direl; (grub_uint8_t *) cdirel - (grub_uint8_t *) direl < (grub_ssize_t) elemsize; @@ -2059,6 +2072,19 @@ grub_btrfs_dir (grub_device_t device, const char *path, char c; struct grub_btrfs_inode inode; struct grub_dirhook_info info; + + if (cdirel == NULL || + grub_add (grub_le_to_cpu16 (cdirel->n), + grub_le_to_cpu16 (cdirel->m), &est_size) || + grub_add (est_size, sizeof (*cdirel), &est_size) || + grub_sub (est_size, sizeof (cdirel->name), &est_size) || + est_size > allocated) + { + grub_errno = GRUB_ERR_OUT_OF_RANGE; + r = -grub_errno; + goto out; + } + err = grub_btrfs_read_inode (data, &inode, cdirel->key.object_id, tree); grub_memset (&info, 0, sizeof (info)); -- 2.33.5