[PATCH] Guard check in module loader against integer overflow

From: David Howells
Date: Tue May 22 2012 - 10:56:16 EST


The check:

if (len < hdr->e_shoff + hdr->e_shnum * sizeof(Elf_Shdr))

may not work if there's an overflow in the right-hand side of the condition.

Signed-off-by: David Howells <dhowells@xxxxxxxxxx>
---

kernel/module.c | 3 ++-
1 files changed, 2 insertions(+), 1 deletions(-)


diff --git a/kernel/module.c b/kernel/module.c
index 78ac6ec..377cb06 100644
--- a/kernel/module.c
+++ b/kernel/module.c
@@ -2429,7 +2429,8 @@ static int copy_and_check(struct load_info *info,
goto free_hdr;
}

- if (len < hdr->e_shoff + hdr->e_shnum * sizeof(Elf_Shdr)) {
+ if (hdr->e_shoff >= len ||
+ hdr->e_shnum * sizeof(Elf_Shdr) > len - hdr->e_shoff) {
err = -ENOEXEC;
goto free_hdr;
}

--
To unsubscribe from this list: send the line "unsubscribe linux-kernel" in
the body of a message to majordomo@xxxxxxxxxxxxxxx
More majordomo info at http://vger.kernel.org/majordomo-info.html
Please read the FAQ at http://www.tux.org/lkml/