From: Lidong Chen <lidong.c...@oracle.com>
The JFS fuzzing revealed an OOB read in grub_jfs_getent(). The crash
was caused by an invalid leaf nodes count, diro->dirpage->header.count,
which was larger than the maximum number of leaf nodes allowed in an
inode. This fix is to ensure that the leaf nodes count is validated in
grub_jfs_opendir() before calling grub_jfs_getent().
On the occasion replace existing raw numbers with newly defined constant.
Signed-off-by: Lidong Chen <lidong.c...@oracle.com>
Reviewed-by: Daniel Kiper <daniel.ki...@oracle.com>
Reviewed-by: Alec Brown <alec.r.br...@oracle.com>
---
grub-core/fs/jfs.c | 17 +++++++++++++++--
1 file changed, 15 insertions(+), 2 deletions(-)
diff --git a/grub-core/fs/jfs.c b/grub-core/fs/jfs.c
index 62e20ef6f..e2fe2850c 100644
--- a/grub-core/fs/jfs.c
+++ b/grub-core/fs/jfs.c
@@ -41,6 +41,12 @@ GRUB_MOD_LICENSE ("GPLv3+");
#define GRUB_JFS_TREE_LEAF 2
+/*
+ * Define max entries stored in-line in an inode.
+ * https://jfs.sourceforge.net/project/pub/jfslayout.pdf
+ */
+#define GRUB_JFS_INODE_INLINE_ENTRIES 8
+
struct grub_jfs_sblock
{
/* The magic for JFS. It should contain the string "JFS1". */
@@ -203,9 +209,9 @@ struct grub_jfs_inode
grub_uint8_t freecnt;
grub_uint8_t freelist;
grub_uint32_t idotdot;
- grub_uint8_t sorted[8];
+ grub_uint8_t sorted[GRUB_JFS_INODE_INLINE_ENTRIES];
} header;
- struct grub_jfs_leaf_dirent dirents[8];
+ struct grub_jfs_leaf_dirent dirents[GRUB_JFS_INODE_INLINE_ENTRIES];
} GRUB_PACKED dir;
/* Fast symlink. */
struct
@@ -453,6 +459,13 @@ grub_jfs_opendir (struct grub_jfs_data *data, struct
grub_jfs_inode *inode)
/* Check if the entire tree is contained within the inode. */
if (inode->file.tree.flags & GRUB_JFS_TREE_LEAF)
{
+ if (inode->dir.header.count > GRUB_JFS_INODE_INLINE_ENTRIES)
+ {
+ grub_free (diro);
+ grub_error (GRUB_ERR_BAD_FS, N_("invalid JFS inode"));
+ return 0;
+ }
+
diro->leaf = inode->dir.dirents;
diro->next_leaf = (struct grub_jfs_leaf_next_dirent *) de;
diro->sorted = inode->dir.header.sorted;
--
2.11.0
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