[122/152] RAMOOPS: Dont overflow over non-allocated regions

Greg KH
2011-01-06T00:38:42Z

From: Ahmed S. Darwish <darwish.07@gmail.com>

commit 1873bb8115e678ad9fd0aac9dbbc68383bc36e06 upstream.

The current code mis-calculates the ramoops header size, leading to an
overflow over the next record at best, or over a non-allocated region at
worst. Fix that calculation.

Signed-off-by: Ahmed S. Darwish <darwish.07@gmail.com>
Acked-by: Marco Stornelli <marco.stornelli@gmail.com>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>

---
drivers/char/ramoops.c | 12 +++++++-----
1 file changed, 7 insertions(+), 5 deletions(-)

--- a/drivers/char/ramoops.c
+++ b/drivers/char/ramoops.c
@@ -27,7 +27,6 @@
#include <linux/ioport.h>

#define RAMOOPS_KERNMSG_HDR "===="
-#define RAMOOPS_HEADER_SIZE (5 + sizeof(struct timeval))

#define RECORD_SIZE 4096

@@ -63,8 +62,8 @@ static void ramoops_do_dump(struct kmsg_
struct ramoops_context, dump);
unsigned long s1_start, s2_start;
unsigned long l1_cpy, l2_cpy;
- int res;
- char *buf;
+ int res, hdr_size;
+ char *buf, *buf_orig;
struct timeval timestamp;

/* Only dump oopses if dump_oops is set */
@@ -72,6 +71,8 @@ static void ramoops_do_dump(struct kmsg_
return;

buf = (char *)(cxt->virt_addr + (cxt->count * RECORD_SIZE));
+ buf_orig = buf;
+
memset(buf, '\0', RECORD_SIZE);
res = sprintf(buf, "%s", RAMOOPS_KERNMSG_HDR);
buf += res;
@@ -79,8 +80,9 @@ static void ramoops_do_dump(struct kmsg_
res = sprintf(buf, "%lu.%lu\n", (long)timestamp.tv_sec, (long)timestamp.tv_usec);
buf += res;

- l2_cpy = min(l2, (unsigned long)(RECORD_SIZE - RAMOOPS_HEADER_SIZE));
- l1_cpy = min(l1, (unsigned long)(RECORD_SIZE - RAMOOPS_HEADER_SIZE) - l2_cpy);
+ hdr_size = buf - buf_orig;
+ l2_cpy = min(l2, (unsigned long)(RECORD_SIZE - hdr_size));
+ l1_cpy = min(l1, (unsigned long)(RECORD_SIZE - hdr_size) - l2_cpy);

s2_start = l2 - l2_cpy;
s1_start = l1 - l1_cpy;