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Message-Id: <20210608183955.280836-2-keescook@chromium.org>
Date: Tue, 8 Jun 2021 11:39:53 -0700
From: Kees Cook <keescook@...omium.org>
To: Andrew Morton <akpm@...ux-foundation.org>
Cc: Kees Cook <keescook@...omium.org>,
Vlastimil Babka <vbabka@...e.cz>,
Marco Elver <elver@...gle.com>,
Christoph Lameter <cl@...ux.com>,
"Lin, Zhenpeng" <zplin@....edu>, Pekka Enberg <penberg@...nel.org>,
David Rientjes <rientjes@...gle.com>,
Joonsoo Kim <iamjoonsoo.kim@....com>,
Roman Gushchin <guro@...com>, linux-kernel@...r.kernel.org,
linux-doc@...r.kernel.org, linux-mm@...ck.org
Subject: [PATCH v4 1/3] mm/slub: Clarify verification reporting
Instead of repeating "Redzone" and "Poison", clarify which sides of
those zones got tripped. Additionally fix column alignment in the
trailer.
Before:
BUG test (Tainted: G B ): Redzone overwritten
...
Redzone (____ptrval____): bb bb bb bb bb bb bb bb ........
Object (____ptrval____): f6 f4 a5 40 1d e8 ...@..
Redzone (____ptrval____): 1a aa ..
Padding (____ptrval____): 00 00 00 00 00 00 00 00 ........
After:
BUG test (Tainted: G B ): Right Redzone overwritten
...
Redzone (____ptrval____): bb bb bb bb bb bb bb bb ........
Object (____ptrval____): f6 f4 a5 40 1d e8 ...@..
Redzone (____ptrval____): 1a aa ..
Padding (____ptrval____): 00 00 00 00 00 00 00 00 ........
The earlier commits that slowly resulted in the "Before" reporting were:
d86bd1bece6f ("mm/slub: support left redzone")
ffc79d288000 ("slub: use print_hex_dump")
2492268472e7 ("SLUB: change error reporting format to follow lockdep loosely")
Signed-off-by: Kees Cook <keescook@...omium.org>
Acked-by: Vlastimil Babka <vbabka@...e.cz>
Link: https://lore.kernel.org/lkml/cfdb11d7-fb8e-e578-c939-f7f5fb69a6bd@suse.cz/
---
Documentation/vm/slub.rst | 10 +++++-----
mm/slub.c | 14 +++++++-------
2 files changed, 12 insertions(+), 12 deletions(-)
diff --git a/Documentation/vm/slub.rst b/Documentation/vm/slub.rst
index 03f294a638bd..d3028554b1e9 100644
--- a/Documentation/vm/slub.rst
+++ b/Documentation/vm/slub.rst
@@ -181,7 +181,7 @@ SLUB Debug output
Here is a sample of slub debug output::
====================================================================
- BUG kmalloc-8: Redzone overwritten
+ BUG kmalloc-8: Right Redzone overwritten
--------------------------------------------------------------------
INFO: 0xc90f6d28-0xc90f6d2b. First byte 0x00 instead of 0xcc
@@ -189,10 +189,10 @@ Here is a sample of slub debug output::
INFO: Object 0xc90f6d20 @offset=3360 fp=0xc90f6d58
INFO: Allocated in get_modalias+0x61/0xf5 age=53 cpu=1 pid=554
- Bytes b4 0xc90f6d10: 00 00 00 00 00 00 00 00 5a 5a 5a 5a 5a 5a 5a 5a ........ZZZZZZZZ
- Object 0xc90f6d20: 31 30 31 39 2e 30 30 35 1019.005
- Redzone 0xc90f6d28: 00 cc cc cc .
- Padding 0xc90f6d50: 5a 5a 5a 5a 5a 5a 5a 5a ZZZZZZZZ
+ Bytes b4 (0xc90f6d10): 00 00 00 00 00 00 00 00 5a 5a 5a 5a 5a 5a 5a 5a ........ZZZZZZZZ
+ Object (0xc90f6d20): 31 30 31 39 2e 30 30 35 1019.005
+ Redzone (0xc90f6d28): 00 cc cc cc .
+ Padding (0xc90f6d50): 5a 5a 5a 5a 5a 5a 5a 5a ZZZZZZZZ
[<c010523d>] dump_trace+0x63/0x1eb
[<c01053df>] show_trace_log_lvl+0x1a/0x2f
diff --git a/mm/slub.c b/mm/slub.c
index 3f96e099817a..f91d9fe7d0d8 100644
--- a/mm/slub.c
+++ b/mm/slub.c
@@ -712,15 +712,15 @@ static void print_trailer(struct kmem_cache *s, struct page *page, u8 *p)
p, p - addr, get_freepointer(s, p));
if (s->flags & SLAB_RED_ZONE)
- print_section(KERN_ERR, "Redzone ", p - s->red_left_pad,
+ print_section(KERN_ERR, "Redzone ", p - s->red_left_pad,
s->red_left_pad);
else if (p > addr + 16)
print_section(KERN_ERR, "Bytes b4 ", p - 16, 16);
- print_section(KERN_ERR, "Object ", p,
+ print_section(KERN_ERR, "Object ", p,
min_t(unsigned int, s->object_size, PAGE_SIZE));
if (s->flags & SLAB_RED_ZONE)
- print_section(KERN_ERR, "Redzone ", p + s->object_size,
+ print_section(KERN_ERR, "Redzone ", p + s->object_size,
s->inuse - s->object_size);
off = get_info_end(s);
@@ -732,7 +732,7 @@ static void print_trailer(struct kmem_cache *s, struct page *page, u8 *p)
if (off != size_from_object(s))
/* Beginning of the filler is the free pointer */
- print_section(KERN_ERR, "Padding ", p + off,
+ print_section(KERN_ERR, "Padding ", p + off,
size_from_object(s) - off);
dump_stack();
@@ -909,11 +909,11 @@ static int check_object(struct kmem_cache *s, struct page *page,
u8 *endobject = object + s->object_size;
if (s->flags & SLAB_RED_ZONE) {
- if (!check_bytes_and_report(s, page, object, "Redzone",
+ if (!check_bytes_and_report(s, page, object, "Left Redzone",
object - s->red_left_pad, val, s->red_left_pad))
return 0;
- if (!check_bytes_and_report(s, page, object, "Redzone",
+ if (!check_bytes_and_report(s, page, object, "Right Redzone",
endobject, val, s->inuse - s->object_size))
return 0;
} else {
@@ -928,7 +928,7 @@ static int check_object(struct kmem_cache *s, struct page *page,
if (val != SLUB_RED_ACTIVE && (s->flags & __OBJECT_POISON) &&
(!check_bytes_and_report(s, page, p, "Poison", p,
POISON_FREE, s->object_size - 1) ||
- !check_bytes_and_report(s, page, p, "Poison",
+ !check_bytes_and_report(s, page, p, "End Poison",
p + s->object_size - 1, POISON_END, 1)))
return 0;
/*
--
2.25.1
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