From: Zhen Lei <thunder.leizhen@xxxxxxxxxx>
The contents of the slab object may contain some magic words and other
useful information that may be helpful in locating problems such as
memory corruption and use-after-free.
To avoid print flooding, dump up to "16 * sizeof(int) = 64" bytes
centered on argument 'ojbect'.
For example:
slab kmalloc-64 start ffff4043802d8b40 pointer offset 24 size 64
[8b40]: 12345678 00000000 8092d000 ffff8000
[8b50]: 00101000 00000000 8199ee00 ffff4043
[8b60]: 00000000 00000000 00000000 00000100
[8b70]: 00000000 9abcdef0 a8744de4 ffffc7fe
Signed-off-by: Zhen Lei <thunder.leizhen@xxxxxxxxxx>
---
mm/slab_common.c | 27 ++++++++++++++++++++++++---
1 file changed, 24 insertions(+), 3 deletions(-)
diff --git a/mm/slab_common.c b/mm/slab_common.c
index ee6ed6dd7ba9fa5..3564e60a2584b12 100644
--- a/mm/slab_common.c
+++ b/mm/slab_common.c
@@ -553,7 +553,7 @@ static void kmem_obj_info(struct kmem_obj_info *kpp, void *object, struct slab *
bool kmem_dump_obj(void *object)
{
char *cp = IS_ENABLED(CONFIG_MMU) ? "" : "/vmalloc";
- int i;
+ int i, object_size = 0;
struct slab *slab;
unsigned long ptroffset;
struct kmem_obj_info kp = { };
@@ -580,12 +580,33 @@ bool kmem_dump_obj(void *object)
ptroffset = ((char *)object - (char *)kp.kp_objp) - kp.kp_data_offset;
pr_cont(" pointer offset %lu", ptroffset);
}
- if (kp.kp_slab_cache && kp.kp_slab_cache->object_size)
- pr_cont(" size %u", kp.kp_slab_cache->object_size);
+ if (kp.kp_slab_cache && kp.kp_slab_cache->object_size) {
+ object_size = kp.kp_slab_cache->object_size;
+ pr_cont(" size %u", object_size);
+ }
if (kp.kp_ret)
pr_cont(" allocated at %pS\n", kp.kp_ret);
else
pr_cont("\n");
+
+ /* Dump a small piece of memory centered on 'object' */
+ if (kp.kp_objp && object_size) {
+ void *p = object;
+ int dump_size = 64;
+
+ p += dump_size / 2;
+ if (p > kp.kp_objp + object_size)
+ p = kp.kp_objp + object_size;
+
+ p -= dump_size;
+ if (p < kp.kp_objp)
+ p = kp.kp_objp;
+
+ dump_size = min(object_size, dump_size);
+ print_hex_dump(KERN_INFO, "",
+ DUMP_PREFIX_ADDRESS_LOW16, 16, 4, p, dump_size, false);
+ }
+
for (i = 0; i < ARRAY_SIZE(kp.kp_stack); i++) {
if (!kp.kp_stack[i])
break;
--
2.34.1
