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fs/ext2: Fix out-of-bounds read for inline extents

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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 <dja@axtens.net>
Signed-off-by: Michael Chang <mchang@suse.com>
Reviewed-by: Daniel Kiper <daniel.kiper@oracle.com>
This commit is contained in:
Michael Chang 2024-05-31 15:14:23 +08:00 committed by Daniel Kiper
parent edd995a26e
commit 7e2f750f0a
1 changed files with 9 additions and 1 deletions
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10
grub-core/fs/ext2.c
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@ -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;