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[198.145.64.163]) by smtp.gmail.com with ESMTPSA id x125sm11185015pfx.201.2021.06.08.11.39.57 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Tue, 08 Jun 2021 11:39:57 -0700 (PDT) From: Kees Cook To: Andrew Morton Cc: Kees Cook , Vlastimil Babka , Marco Elver , Christoph Lameter , "Lin, Zhenpeng" , Pekka Enberg , David Rientjes , Joonsoo Kim , Roman Gushchin , linux-kernel@vger.kernel.org, linux-doc@vger.kernel.org, linux-mm@kvack.org Subject: [PATCH v4 1/3] mm/slub: Clarify verification reporting Date: Tue, 8 Jun 2021 11:39:53 -0700 Message-Id: <20210608183955.280836-2-keescook@chromium.org> X-Mailer: git-send-email 2.25.1 In-Reply-To: <20210608183955.280836-1-keescook@chromium.org> References: <20210608183955.280836-1-keescook@chromium.org> MIME-Version: 1.0 X-Patch-Hashes: v=1; h=sha256; g=178be2f9d2e784ee9bf12a0f196176c115be9fbb; i=U+vADmko1G4lZ39LsoUZb95Wrx2rzv1r6guaqRqH67M=; m=KNPYS4ZBPM+uSQxSrL5WKoyUoDfTLfQIvACRYbVbr6o=; p=oVLORPkeeRwgt0gc55edlRvCMc3IvI98MP3RDST0Gds= X-Patch-Sig: m=pgp; i=keescook@chromium.org; s=0x0x8972F4DFDC6DC026; b=iQIzBAABCgAdFiEEpcP2jyKd1g9yPm4TiXL039xtwCYFAmC/uXoACgkQiXL039xtwCZwew/+M13 4wKVrclvxFWQ7U4l1afq0WF/fGE8hgsFeBYQox+dbgIZbDFA56wtNup/udYkNnkiz1muhxBERvtpx V/1Ap4LRawWE41JgshDMfF7c8rJRoy+lolYEjMbXFvs/YxH6TSqFqHXMfy70QRfraczox8kT8mwaB 3l6enWQxhMCeTygt27lZ+F417VXJD/bM1zyLrC3FE0JJ9dJ/uuiE7ZzTMY8DMLgpu+VoSwNqWL4zR lUfNYyxwQz5/3puRkpungw97NK5d14+Ug+tcWImkEGsbPD2iD6Rlra8JVpGa5XTSsqlBOu8Mrqo/q UmqQalgmoWOamnvCiAaBI24YHpLU8pQq178JqK2O0owPhbC8mlNpTEVgZ43GF1hkDhhPQ/QvwRz0Z XC+1WyhwjUT9FRHHhPhRWOgxpY5Q8illryl21dK+9IbuLYRyX1s6Nh4fERJRqltrb6hKHePAUbGzD i5Nh9dwYX4skY48Oui7IL5I+KZsycdwLSXDfQNvN+MmqVmN35gOMJYvq6Kd+LFCDwzAamQyyXUTPp OkUA89+s5SQ958kNjTvicCs7xe5hmRareo/aslj2P9P//WAzu0x0AjGvBXx9/NZ9f0z9/spWcxI4+ Qtjy5K0z/S5nGC6E4tBifF99GPbi0/Y3ge/0NMroeVZrLwbkWQV2KuCPMP/hB14c= Content-Transfer-Encoding: 8bit Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org 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 Acked-by: Vlastimil Babka 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 [] dump_trace+0x63/0x1eb [] 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