RAMOOPS: Don't overflow over non-allocated regions
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>
Cc: stable@kernel.org
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
diff --git a/drivers/char/ramoops.c b/drivers/char/ramoops.c
index 73dcb0e..d3d63be 100644
--- a/drivers/char/ramoops.c
+++ b/drivers/char/ramoops.c
@@ -29,7 +29,6 @@
#include <linux/ramoops.h>
#define RAMOOPS_KERNMSG_HDR "===="
-#define RAMOOPS_HEADER_SIZE (5 + sizeof(struct timeval))
#define RECORD_SIZE 4096
@@ -65,8 +64,8 @@
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 */
@@ -74,6 +73,8 @@
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;
@@ -81,8 +82,9 @@
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;