From 3a2e7f47d71e1df86acc1dda6826890b6546a4e1 Mon Sep 17 00:00:00 2001 From: Pavel Emelyanov Date: Tue, 29 Apr 2008 00:59:24 -0700 Subject: binfmt_misc.c: avoid potential kernel stack overflow This can be triggered with root help only, but... Register the ":text:E::txt::/root/cat.txt:' rule in binfmt_misc (by root) and try launching the cat.txt file (by anyone) :) The result is - the endless recursion in the load_misc_binary -> open_exec -> load_misc_binary chain and stack overflow. There's a similar problem with binfmt_script, and there's a sh_bang memner on linux_binprm structure to handle this, but simply raising this in binfmt_misc may break some setups when the interpreter of some misc binaries is a script. So the proposal is to turn sh_bang into a bit, add a new one (the misc_bang) and raise it in load_misc_binary. After this, even if we set up the misc -> script -> misc loop for binfmts one of them will step on its own bang and exit. Signed-off-by: Pavel Emelyanov Signed-off-by: Andrew Morton Signed-off-by: Linus Torvalds --- include/linux/binfmts.h | 3 ++- 1 file changed, 2 insertions(+), 1 deletion(-) (limited to 'include/linux/binfmts.h') diff --git a/include/linux/binfmts.h b/include/linux/binfmts.h index 1dd7567..b512e48 100644 --- a/include/linux/binfmts.h +++ b/include/linux/binfmts.h @@ -34,7 +34,8 @@ struct linux_binprm{ #endif struct mm_struct *mm; unsigned long p; /* current top of mem */ - int sh_bang; + unsigned int sh_bang:1, + misc_bang:1; struct file * file; int e_uid, e_gid; kernel_cap_t cap_inheritable, cap_permitted; -- cgit v1.1