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[198.145.64.163]) by smtp.gmail.com with ESMTPSA id w23sm11091704pfn.142.2020.10.09.12.54.16 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Fri, 09 Oct 2020 12:54:16 -0700 (PDT) From: Kees Cook To: Andrew Morton Cc: Kees Cook , Marco Elver , Jonathan Corbet , Christoph Lameter , Pekka Enberg , David Rientjes , Joonsoo Kim , Vlastimil Babka , Roman Gushchin , linux-kernel@vger.kernel.org, linux-doc@vger.kernel.org, linux-mm@kvack.org Subject: [PATCH v2 1/3] mm/slub: Clarify verification reporting Date: Fri, 9 Oct 2020 12:54:09 -0700 Message-Id: <20201009195411.4018141-2-keescook@chromium.org> X-Mailer: git-send-email 2.25.1 In-Reply-To: <20201009195411.4018141-1-keescook@chromium.org> References: <20201009195411.4018141-1-keescook@chromium.org> MIME-Version: 1.0 Content-Transfer-Encoding: quoted-printable X-Bogosity: Ham, tests=bogofilter, spamicity=0.000000, version=1.2.4 Sender: owner-linux-mm@kvack.org Precedence: bulk X-Loop: owner-majordomo@kvack.org List-ID: 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 ........ Fixes: d86bd1bece6f ("mm/slub: support left redzone") Fixes: ffc79d288000 ("slub: use print_hex_dump") Fixes: 2492268472e7 ("SLUB: change error reporting format to follow lockd= ep loosely") Signed-off-by: Kees Cook --- 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 289d231cee97..77c7a3331eda 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:: =20 =3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D= =3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D= =3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D - BUG kmalloc-8: Redzone overwritten + BUG kmalloc-8: Right Redzone overwritten -------------------------------------------------------------------- =20 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=3D3360 fp=3D0xc90f6d58 INFO: Allocated in get_modalias+0x61/0xf5 age=3D53 cpu=3D1 pid=3D554 =20 - 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 1= 019.005 - Redzone 0xc90f6d28: 00 cc cc cc . - Padding 0xc90f6d50: 5a 5a 5a 5a 5a 5a 5a 5a Z= ZZZZZZZ + 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 =20 [] dump_trace+0x63/0x1eb [] show_trace_log_lvl+0x1a/0x2f diff --git a/mm/slub.c b/mm/slub.c index 6d3574013b2f..f4f1d63f0ab9 100644 --- a/mm/slub.c +++ b/mm/slub.c @@ -698,15 +698,15 @@ static void print_trailer(struct kmem_cache *s, str= uct page *page, u8 *p) p, p - addr, get_freepointer(s, p)); =20 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); =20 - 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); =20 off =3D get_info_end(s); @@ -718,7 +718,7 @@ static void print_trailer(struct kmem_cache *s, struc= t page *page, u8 *p) =20 if (off !=3D 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); =20 dump_stack(); @@ -895,11 +895,11 @@ static int check_object(struct kmem_cache *s, struc= t page *page, u8 *endobject =3D object + s->object_size; =20 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; =20 - 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 { @@ -914,7 +914,7 @@ static int check_object(struct kmem_cache *s, struct = page *page, if (val !=3D 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; /* --=20 2.25.1