From 0000000000000000000000000000000000000000 Mon Sep 17 00:00:00 2001 From: Daniel Axtens Date: Mon, 18 Jan 2021 15:47:24 +1100 Subject: [PATCH] fs/jfs: Catch infinite recursion It's possible with a fuzzed filesystem for JFS to keep getblk()-ing the same data over and over again, leading to stack exhaustion. Check if we'd be calling the function with exactly the same data as was passed in, and if so abort. I'm not sure what the performance impact of this is and am open to better ideas. Signed-off-by: Daniel Axtens Reviewed-by: Daniel Kiper --- grub-core/fs/jfs.c | 11 ++++++++++- 1 file changed, 10 insertions(+), 1 deletion(-) diff --git a/grub-core/fs/jfs.c b/grub-core/fs/jfs.c index 6e81f37da..20d966abf 100644 --- a/grub-core/fs/jfs.c +++ b/grub-core/fs/jfs.c @@ -304,7 +304,16 @@ getblk (struct grub_jfs_treehead *treehead, << (grub_le_to_cpu16 (data->sblock.log2_blksz) - GRUB_DISK_SECTOR_BITS), 0, sizeof (*tree), (char *) tree)) - ret = getblk (&tree->treehead, &tree->extents[0], 254, data, blk); + { + if (grub_memcmp (&tree->treehead, treehead, sizeof (struct grub_jfs_treehead)) || + grub_memcmp (&tree->extents, extents, 254 * sizeof (struct grub_jfs_tree_extent))) + ret = getblk (&tree->treehead, &tree->extents[0], 254, data, blk); + else + { + grub_error (GRUB_ERR_BAD_FS, "jfs: infinite recursion detected"); + ret = -1; + } + } grub_free (tree); return ret; }