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authorArjan van de Ven <arjan@infradead.org>2009-10-13 21:17:36 (GMT)
committerJames Morris <jmorris@namei.org>2009-10-13 21:17:36 (GMT)
commit825332e4ff1373c55d931b49408df7ec2298f71e (patch)
treef489a311e576eb1b45ff62cbc0cccbe3bea2baeb /kernel/capability.c
parenta27ab9f26b729326778271c1efd895aef4fda1c4 (diff)
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capabilities: simplify bound checks for copy_from_user()
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@linux.intel.com> Acked-by: James Morris <jmorris@namei.org> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: James Morris <jmorris@namei.org>
Diffstat (limited to 'kernel/capability.c')
-rw-r--r--kernel/capability.c9
1 files changed, 6 insertions, 3 deletions
diff --git a/kernel/capability.c b/kernel/capability.c
index 4e17041..c2316d3 100644
--- a/kernel/capability.c
+++ b/kernel/capability.c
@@ -238,7 +238,7 @@ 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 +255,11 @@ 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 > sizeof(kdata))
+ return -EFAULT;
+
+ if (copy_from_user(&kdata, data, copybytes))
return -EFAULT;
for (i = 0; i < tocopy; i++) {