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From 0000000000000000000000000000000000000000 Mon Sep 17 00:00:00 2001
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From: Darren Kenny <darren.kenny@oracle.com>
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Date: Tue, 29 Mar 2022 10:49:56 +0000
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Subject: [PATCH] fs/btrfs: Fix several fuzz issues with invalid dir item
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sizing
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According to the btrfs code in Linux, the structure of a directory item
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leaf should be of the form:
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|struct btrfs_dir_item|name|data|
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in GRUB the name len and data len are in the grub_btrfs_dir_item
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structure's n and m fields respectively.
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The combined size of the structure, name and data should be less than
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the allocated memory, a difference to the Linux kernel's struct
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btrfs_dir_item is that the grub_btrfs_dir_item has an extra field for
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where the name is stored, so we adjust for that too.
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Signed-off-by: Darren Kenny <darren.kenny@oracle.com>
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Reviewed-by: Daniel Kiper <daniel.kiper@oracle.com>
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(cherry picked from commit 6d3f06c0b6a8992b9b1bb0e62af93ac5ff2781f0)
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[rharwood: we've an extra variable here]
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Signed-off-by: Robbie Harwood <rharwood@redhat.com>
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(cherry picked from commit e3e21b9a81aea09dd43368cf097c1029a8380d82)
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---
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grub-core/fs/btrfs.c | 26 ++++++++++++++++++++++++++
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1 file changed, 26 insertions(+)
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diff --git a/grub-core/fs/btrfs.c b/grub-core/fs/btrfs.c
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index 4cc86e9b79..f3ab64e098 100644
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--- a/grub-core/fs/btrfs.c
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+++ b/grub-core/fs/btrfs.c
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@@ -2254,6 +2254,7 @@ grub_btrfs_dir (grub_device_t device, const char *path,
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grub_uint64_t tree;
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grub_uint8_t type;
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char *new_path = NULL;
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+ grub_size_t est_size = 0;
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if (!data)
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return grub_errno;
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@@ -2320,6 +2321,18 @@ grub_btrfs_dir (grub_device_t device, const char *path,
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break;
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}
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+ if (direl == NULL ||
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+ grub_add (grub_le_to_cpu16 (direl->n),
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+ grub_le_to_cpu16 (direl->m), &est_size) ||
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+ grub_add (est_size, sizeof (*direl), &est_size) ||
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+ grub_sub (est_size, sizeof (direl->name), &est_size) ||
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+ est_size > allocated)
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+ {
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+ grub_errno = GRUB_ERR_OUT_OF_RANGE;
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+ r = -grub_errno;
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+ goto out;
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+ }
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+
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for (cdirel = direl;
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(grub_uint8_t *) cdirel - (grub_uint8_t *) direl
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< (grub_ssize_t) elemsize;
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@@ -2330,6 +2343,19 @@ grub_btrfs_dir (grub_device_t device, const char *path,
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char c;
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struct grub_btrfs_inode inode;
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struct grub_dirhook_info info;
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+
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+ if (cdirel == NULL ||
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+ grub_add (grub_le_to_cpu16 (cdirel->n),
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+ grub_le_to_cpu16 (cdirel->m), &est_size) ||
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+ grub_add (est_size, sizeof (*cdirel), &est_size) ||
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+ grub_sub (est_size, sizeof (cdirel->name), &est_size) ||
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+ est_size > allocated)
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+ {
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+ grub_errno = GRUB_ERR_OUT_OF_RANGE;
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+ r = -grub_errno;
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+ goto out;
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+ }
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+
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err = grub_btrfs_read_inode (data, &inode, cdirel->key.object_id,
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tree);
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grub_memset (&info, 0, sizeof (info));
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