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authorDan Carpenter <dan.carpenter@oracle.com>2013-10-29 22:06:04 +0300
committerGreg Kroah-Hartman <gregkh@linuxfoundation.org>2013-11-13 12:01:49 +0900
commitcc51af932905754ad594f8d1fc02d61073b7236f (patch)
tree023afccd4a608a0d7e0564082bfc9a79eb626908
parent8c373c185f096a93a70f7ebba792cb16f2a8530e (diff)
downloadlwn-cc51af932905754ad594f8d1fc02d61073b7236f.tar.gz
lwn-cc51af932905754ad594f8d1fc02d61073b7236f.zip
uml: check length in exitcode_proc_write()
commit 201f99f170df14ba52ea4c52847779042b7a623b upstream. We don't cap the size of buffer from the user so we could write past the end of the array here. Only root can write to this file. Reported-by: Nico Golde <nico@ngolde.de> Reported-by: Fabian Yamaguchi <fabs@goesec.de> Signed-off-by: Dan Carpenter <dan.carpenter@oracle.com> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
-rw-r--r--arch/um/kernel/exitcode.c4
1 files changed, 3 insertions, 1 deletions
diff --git a/arch/um/kernel/exitcode.c b/arch/um/kernel/exitcode.c
index 829df49dee99..41ebbfebb333 100644
--- a/arch/um/kernel/exitcode.c
+++ b/arch/um/kernel/exitcode.c
@@ -40,9 +40,11 @@ static ssize_t exitcode_proc_write(struct file *file,
const char __user *buffer, size_t count, loff_t *pos)
{
char *end, buf[sizeof("nnnnn\0")];
+ size_t size;
int tmp;
- if (copy_from_user(buf, buffer, count))
+ size = min(count, sizeof(buf));
+ if (copy_from_user(buf, buffer, size))
return -EFAULT;
tmp = simple_strtol(buf, &end, 0);