[PATCH v4 1/3] mm/slub: Clarify verification reporting
From: Kees Cook <hidden>
Date: 2021-06-08 18:45:27
Also in:
linux-mm, lkml
Subsystem:
documentation, memory management, slab allocator, the rest · Maintainers:
Jonathan Corbet, Andrew Morton, Vlastimil Babka, Harry Yoo, Linus Torvalds
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 <redacted>
Acked-by: Vlastimil Babka <redacted>
Link: https://lore.kernel.org/lkml/cfdb11d7-fb8e-e578-c939-f7f5fb69a6bd@suse.cz/ (local)
---
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