From: Michael Chang <mch...@suse.com>
When inline extents are used, i.e. the extent tree depth equals zero,
a maximum of four entries can fit into the inode's data block. If the
extent header states a number of entries greater than four the current
ext2 implementation causes an out-of-bounds read. Fix this issue by
capping the number of extents to four when reading inline extents.
Reported-by: Daniel Axtens <d...@axtens.net>
Signed-off-by: Michael Chang <mch...@suse.com>
Reviewed-by: Daniel Kiper <daniel.ki...@oracle.com>
---
grub-core/fs/ext2.c | 10 +++++++++-
1 file changed, 9 insertions(+), 1 deletion(-)
diff --git a/grub-core/fs/ext2.c b/grub-core/fs/ext2.c
index e1cc5e62a..3f9f6b208 100644
--- a/grub-core/fs/ext2.c
+++ b/grub-core/fs/ext2.c
@@ -495,6 +495,8 @@ grub_ext2_read_block (grub_fshelp_node_t node,
grub_disk_addr_t fileblock)
struct grub_ext4_extent *ext;
int i;
grub_disk_addr_t ret;
+ grub_uint16_t nent;
+ const grub_uint16_t max_inline_ext = sizeof (inode->blocks) / sizeof
(*ext) - 1; /* Minus 1 extent header. */
if (grub_ext4_find_leaf (data, (struct grub_ext4_extent_header *)
inode->blocks.dir_blocks,
fileblock, &leaf) != GRUB_ERR_NONE)
@@ -508,7 +510,13 @@ grub_ext2_read_block (grub_fshelp_node_t node,
grub_disk_addr_t fileblock)
return 0;
ext = (struct grub_ext4_extent *) (leaf + 1);
- for (i = 0; i < grub_le_to_cpu16 (leaf->entries); i++)
+
+ nent = grub_le_to_cpu16 (leaf->entries);
+
+ if (leaf->depth == 0)
+ nent = grub_min (nent, max_inline_ext);
+
+ for (i = 0; i < nent; i++)
{
if (fileblock < grub_le_to_cpu32 (ext[i].block))
break;
--
2.11.0
_______________________________________________
Grub-devel mailing list
Grub-devel@gnu.org
https://lists.gnu.org/mailman/listinfo/grub-devel
