[<prev] [next>] [<thread-prev] [thread-next>] [day] [month] [year] [list]
Message-ID: <20090926205336.77bc5b21@infradead.org>
Date: Sat, 26 Sep 2009 20:53:36 +0200
From: Arjan van de Ven <arjan@...radead.org>
To: Arjan van de Ven <arjan@...radead.org>
Cc: linux-kernel@...r.kernel.org, torvalds@...ux-foundation.org,
mingo@...e.hu, jmorris@...i.org
Subject: [PATCH 7/9] Simplify bound checks in capabilities for
copy_from_user
From: Arjan van de Ven <arjan@...ux.intel.com>
Subject: [PATCH 7/9] Simplify bound checks in capabilities for copy_from_user
CC: James Morris <jmorris@...ei.org>
The capabilities syscall has a copy_from_user() call where gcc currently
cannot prove to itself that the copy is always within bounds.
This patch adds a very explicity bound check to prove to gcc that
this copy_from_user cannot overflow its destination buffer.
Signed-off-by: Arjan van de Ven <arjan@...ux.intel.com>
diff --git a/kernel/capability.c b/kernel/capability.c
index 4e17041..204f11f 100644
--- a/kernel/capability.c
+++ b/kernel/capability.c
@@ -238,7 +241,7 @@ SYSCALL_DEFINE2(capget, cap_user_header_t, header, cap_user_data_t, dataptr)
SYSCALL_DEFINE2(capset, cap_user_header_t, header, const cap_user_data_t, data)
{
struct __user_cap_data_struct kdata[_KERNEL_CAPABILITY_U32S];
- unsigned i, tocopy;
+ unsigned i, tocopy, copybytes;
kernel_cap_t inheritable, permitted, effective;
struct cred *new;
int ret;
@@ -255,8 +258,11 @@ SYSCALL_DEFINE2(capset, cap_user_header_t, header, const cap_user_data_t, data)
if (pid != 0 && pid != task_pid_vnr(current))
return -EPERM;
- if (copy_from_user(&kdata, data,
- tocopy * sizeof(struct __user_cap_data_struct)))
+ copybytes = tocopy * sizeof(struct __user_cap_data_struct);
+ if (copybytes > _KERNEL_CAPABILITY_U32S)
+ return -EFAULT;
+
+ if (copy_from_user(&kdata, data, copybytes))
return -EFAULT;
for (i = 0; i < tocopy; i++) {
--
Arjan van de Ven Intel Open Source Technology Centre
For development, discussion and tips for power savings,
visit http://www.lesswatts.org
--
To unsubscribe from this list: send the line "unsubscribe linux-kernel" in
the body of a message to majordomo@...r.kernel.org
More majordomo info at http://vger.kernel.org/majordomo-info.html
Please read the FAQ at http://www.tux.org/lkml/
Powered by blists - more mailing lists