The patch titled
Subject: slub: print raw pointer addresses when debugging
has been added to the -mm tree. Its filename is
slub-print-raw-pointer-addresses-when-debugging.patch
This patch should soon appear at
https://ozlabs.org/~akpm/mmots/broken-out/slub-print-raw-pointer-addresses-when-debugging.patch
and later at
https://ozlabs.org/~akpm/mmotm/broken-out/slub-print-raw-pointer-addresses-when-debugging.patch
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*** Remember to use Documentation/process/submit-checklist.rst when testing your code ***
The -mm tree is included into linux-next and is updated
there every 3-4 working days
------------------------------------------------------
From: Stephen Boyd <swboyd@xxxxxxxxxxxx>
Subject: slub: print raw pointer addresses when debugging
Obscuring the pointers that slub shows when debugging makes for some
confusing slub debug messages:
Padding overwritten. 0x0000000079f0674a-0x000000000d4dce17
Those addresses are hashed for kernel security reasons. If we're trying
to be secure with slub_debug on the commandline we have some big problems
given that we dump whole chunks of kernel memory to the kernel logs.
Let's use %px here and dump buffers with the actual address for the buffer
instead of the hashed version so that the logs are meaningful. This also
helps if a kernel address is in some slub debug report so we can figure
out that the object is referencing itself.
Link: https://lkml.kernel.org/r/20210520013539.3733631-3-swboyd@xxxxxxxxxxxx
Signed-off-by: Stephen Boyd <swboyd@xxxxxxxxxxxx>
Cc: Christoph Lameter <cl@xxxxxxxxx>
Cc: David Rientjes <rientjes@xxxxxxxxxx>
Cc: Joonsoo Kim <iamjoonsoo.kim@xxxxxxx>
Cc: Pekka Enberg <penberg@xxxxxxxxxx>
Cc: Vlastimil Babka <vbabka@xxxxxxx>
Signed-off-by: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx>
---
mm/slub.c | 24 ++++++++++++------------
1 file changed, 12 insertions(+), 12 deletions(-)
--- a/mm/slub.c~slub-print-raw-pointer-addresses-when-debugging
+++ a/mm/slub.c
@@ -568,7 +568,7 @@ static void print_section(char *level, c
unsigned int length)
{
metadata_access_enable();
- print_hex_dump(level, kasan_reset_tag(text), DUMP_PREFIX_ADDRESS,
+ print_hex_dump(level, kasan_reset_tag(text), DUMP_PREFIX_RAW_ADDRESS,
16, 1, addr, length, 1);
metadata_access_disable();
}
@@ -669,7 +669,7 @@ void print_tracking(struct kmem_cache *s
static void print_page_info(struct page *page)
{
- pr_err("Slab 0x%p objects=%u used=%u fp=0x%p flags=%#lx(%pGp)\n",
+ pr_err("Slab 0x%px objects=%u used=%u fp=0x%px flags=%#lx(%pGp)\n",
page, page->objects, page->inuse, page->freelist,
page->flags, &page->flags);
@@ -729,7 +729,7 @@ static void print_trailer(struct kmem_ca
print_page_info(page);
- pr_err("Object 0x%p @offset=%tu fp=0x%p\n\n",
+ pr_err("Object 0x%px @offset=%tu fp=0x%px\n\n",
p, p - addr, get_freepointer(s, p));
if (s->flags & SLAB_RED_ZONE)
@@ -805,7 +805,7 @@ static void init_object(struct kmem_cach
static void restore_bytes(struct kmem_cache *s, char *message, u8 data,
void *from, void *to)
{
- slab_fix(s, "Restoring 0x%p-0x%p=0x%x\n", from, to - 1, data);
+ slab_fix(s, "Restoring 0x%px-0x%px=0x%x\n", from, to - 1, data);
memset(from, data, to - from);
}
@@ -831,7 +831,7 @@ static int check_bytes_and_report(struct
goto skip_bug_print;
slab_bug(s, "%s overwritten", what);
- pr_err("0x%p-0x%p @offset=%tu. First byte 0x%x instead of 0x%x\n",
+ pr_err("0x%px-0x%px @offset=%tu. First byte 0x%x instead of 0x%x\n",
fault, end - 1, fault - addr,
fault[0], value);
print_trailer(s, page, object);
@@ -925,7 +925,7 @@ static int slab_pad_check(struct kmem_ca
while (end > fault && end[-1] == POISON_INUSE)
end--;
- slab_err(s, page, "Padding overwritten. 0x%p-0x%p @offset=%tu",
+ slab_err(s, page, "Padding overwritten. 0x%px-0x%px @offset=%tu",
fault, end - 1, fault - start);
print_section(KERN_ERR, "Padding ", pad, remainder);
@@ -1073,7 +1073,7 @@ static void trace(struct kmem_cache *s,
int alloc)
{
if (s->flags & SLAB_TRACE) {
- pr_info("TRACE %s %s 0x%p inuse=%d fp=0x%p\n",
+ pr_info("TRACE %s %s 0x%px inuse=%d fp=0x%px\n",
s->name,
alloc ? "alloc" : "free",
object, page->inuse,
@@ -1218,7 +1218,7 @@ static inline int free_consistency_check
struct page *page, void *object, unsigned long addr)
{
if (!check_valid_pointer(s, page, object)) {
- slab_err(s, page, "Invalid object pointer 0x%p", object);
+ slab_err(s, page, "Invalid object pointer 0x%px", object);
return 0;
}
@@ -1232,10 +1232,10 @@ static inline int free_consistency_check
if (unlikely(s != page->slab_cache)) {
if (!PageSlab(page)) {
- slab_err(s, page, "Attempt to free object(0x%p) outside of slab",
+ slab_err(s, page, "Attempt to free object(0x%px) outside of slab",
object);
} else if (!page->slab_cache) {
- pr_err("SLUB <none>: no slab for object 0x%p.\n",
+ pr_err("SLUB <none>: no slab for object 0x%px.\n",
object);
dump_stack();
} else
@@ -1295,7 +1295,7 @@ out:
slab_unlock(page);
spin_unlock_irqrestore(&n->list_lock, flags);
if (!ret)
- slab_fix(s, "Object at 0x%p not freed", object);
+ slab_fix(s, "Object at 0x%px not freed", object);
return ret;
}
@@ -3931,7 +3931,7 @@ static void list_slab_objects(struct kme
for_each_object(p, s, addr, page->objects) {
if (!test_bit(__obj_to_index(s, addr, p), map)) {
- pr_err("Object 0x%p @offset=%tu\n", p, p - addr);
+ pr_err("Object 0x%px @offset=%tu\n", p, p - addr);
print_tracking(s, p);
}
}
_
Patches currently in -mm which might be from swboyd@xxxxxxxxxxxx are
lib-hexdump-add-a-raw-pointer-printing-format-for-slub-debugging.patch
slub-print-raw-pointer-addresses-when-debugging.patch
slub-actually-use-message-in-restore_bytes.patch
buildid-only-consider-gnu-notes-for-build-id-parsing.patch
buildid-add-api-to-parse-build-id-out-of-buffer.patch
buildid-stash-away-kernels-build-id-on-init.patch
buildid-stash-away-kernels-build-id-on-init-fix.patch
dump_stack-add-vmlinux-build-id-to-stack-traces.patch
module-add-printk-formats-to-add-module-build-id-to-stacktraces.patch
arm64-stacktrace-use-%psb-for-backtrace-printing.patch
x86-dumpstack-use-%psb-%pbb-for-backtrace-printing.patch
scripts-decode_stacktracesh-support-debuginfod.patch
scripts-decode_stacktracesh-silence-stderr-messages-from-addr2line-nm.patch
scripts-decode_stacktracesh-indicate-auto-can-be-used-for-base-path.patch
buildid-mark-some-arguments-const.patch
buildid-fix-kernel-doc-notation.patch
kdump-use-vmlinux_build_id-to-simplify.patch
