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authorKees Cook <keescook@chromium.org>2021-06-15 18:23:19 -0700
committerLinus Torvalds <torvalds@linux-foundation.org>2021-06-16 09:24:42 -0700
commit8669dbab2ae56085c128894b181c2aa50f97e368 (patch)
treebe64c3d2b5c850698853f823a5eac615c5e5aae4 /Documentation
parent099dd6878b9b12d6bbfa6bf29ce0c8ddd38f6901 (diff)
mm/slub: clarify verification reporting
Patch series "Actually fix freelist pointer vs redzoning", v4. This fixes redzoning vs the freelist pointer (both for middle-position and very small caches). Both are "theoretical" fixes, in that I see no evidence of such small-sized caches actually be used in the kernel, but that's no reason to let the bugs continue to exist, especially since people doing local development keep tripping over it. :) This patch (of 3): 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") Link: https://lkml.kernel.org/r/20210608183955.280836-1-keescook@chromium.org Link: https://lkml.kernel.org/r/20210608183955.280836-2-keescook@chromium.org Link: https://lore.kernel.org/lkml/cfdb11d7-fb8e-e578-c939-f7f5fb69a6bd@suse.cz/ Signed-off-by: Kees Cook <keescook@chromium.org> Acked-by: Vlastimil Babka <vbabka@suse.cz> Cc: Marco Elver <elver@google.com> Cc: "Lin, Zhenpeng" <zplin@psu.edu> Cc: Christoph Lameter <cl@linux.com> Cc: Pekka Enberg <penberg@kernel.org> Cc: David Rientjes <rientjes@google.com> Cc: Joonsoo Kim <iamjoonsoo.kim@lge.com> Cc: Roman Gushchin <guro@fb.com> Cc: <stable@vger.kernel.org> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Diffstat (limited to 'Documentation')
-rw-r--r--Documentation/vm/slub.rst10
1 files changed, 5 insertions, 5 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