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McKenney" , Frederic Weisbecker , Neeraj Upadhyay , Joel Fernandes , Josh Triplett , Boqun Feng , Mathieu Desnoyers , Lai Jiangshan , Zqiang , rcu@vger.kernel.org, linux-kernel@vger.kernel.org Cc: Zhen Lei Subject: [PATCH v6 4/5] mm: Dump the memory of slab object in kmem_dump_obj() Date: Fri, 4 Aug 2023 17:11:34 +0800 Message-Id: <20230804091136.1177-5-thunder.leizhen@huaweicloud.com> X-Mailer: git-send-email 2.37.3.windows.1 In-Reply-To: <20230804091136.1177-1-thunder.leizhen@huaweicloud.com> References: <20230804091136.1177-1-thunder.leizhen@huaweicloud.com> MIME-Version: 1.0 Content-Transfer-Encoding: 8bit X-CM-TRANSID:gCh0CgBH_rHLwMxk2KskPg--.58335S8 X-Coremail-Antispam: 1UD129KBjvJXoW7Ary7WFWDKrWxKF1rKFW8tFb_yoW8tw15pr 9xCryxG3yxJrnrurs7J3WkXF15G3ykC3WkGaya9r17Zw18Jr48u3Z7JF9FkFWUAa1Fq39F yrZ0vFsagFyUJaUanT9S1TB71UUUUUUqnTZGkaVYY2UrUUUUjbIjqfuFe4nvWSU5nxnvy2 9KBjDU0xBIdaVrnRJUUUP2b4IE77IF4wAFF20E14v26rWj6s0DM7CY07I20VC2zVCF04k2 6cxKx2IYs7xG6r1S6rWUM7CIcVAFz4kK6r1j6r18M28IrcIa0xkI8VA2jI8067AKxVWUAV Cq3wA2048vs2IY020Ec7CjxVAFwI0_Xr0E3s1l8cAvFVAK0II2c7xJM28CjxkF64kEwVA0 rcxSw2x7M28EF7xvwVC0I7IYx2IY67AKxVW7JVWDJwA2z4x0Y4vE2Ix0cI8IcVCY1x0267 AKxVW8Jr0_Cr1UM28EF7xvwVC2z280aVAFwI0_GcCE3s1l84ACjcxK6I8E87Iv6xkF7I0E 14v26rxl6s0DM2AIxVAIcxkEcVAq07x20xvEncxIr21l5I8CrVACY4xI64kE6c02F40Ex7 xfMcIj6xIIjxv20xvE14v26r1j6r18McIj6I8E87Iv67AKxVWUJVW8JwAm72CE4IkC6x0Y z7v_Jr0_Gr1lF7xvr2IYc2Ij64vIr41lFIxGxcIEc7CjxVA2Y2ka0xkIwI1lw4CEc2x0rV AKj4xxMxAIw28IcxkI7VAKI48JMxC20s026xCaFVCjc4AY6r1j6r4UMI8I3I0E5I8CrVAF wI0_Jr0_Jr4lx2IqxVCjr7xvwVAFwI0_JrI_JrWlx4CE17CEb7AF67AKxVW8ZVWrXwCIc4 0Y0x0EwIxGrwCI42IY6xIIjxv20xvE14v26r1j6r1xMIIF0xvE2Ix0cI8IcVCY1x0267AK xVW8Jr0_Cr1UMIIF0xvE42xK8VAvwI8IcIk0rVWUJVWUCwCI42IY6I8E87Iv67AKxVWUJV W8JwCI42IY6I8E87Iv6xkF7I0E14v26r4UJVWxJrUvcSsGvfC2KfnxnUUI43ZEXa7IU192 -UUUUUU== X-CM-SenderInfo: hwkx0vthuozvpl2kv046kxt4xhlfz01xgou0bp/ X-CFilter-Loop: Reflected X-Rspam-User: X-Rspamd-Server: rspam12 X-Rspamd-Queue-Id: 59D80C001B X-Stat-Signature: rhamihf4uopf6s5ysewdmoheiipz1s7o X-HE-Tag: 1691140312-244179 X-HE-Meta: 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 P2Yb5Zti zorrcExxEy1p0VlLUvPVC08Fd6v3VT+wxaGuRfjSMbSyBiN554gy9UxFX60/VHW76KdmdNEoV0ARRRn1Ehz5AbZe+OUNgr2GGq+F5vjz2Ymy79JtMadmA8LQZXAG+hvEBDQQM4+RerBmtktQZAy+yspJe93nH/2SdRrtRX5IAVJmTJ/W+/49HHwmkuNH4qutveHiun91dTU/PGVb+DjcVmoCyv03woFUlI/bcn/rfKSRpDGWwjyDAhuKj/YshkMJHRK7jTUa3uAUiJsjfwUTyJ6lBSdNHee4xxwCmzaaXG5wZ71zc6Lw8W567vA== 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: From: Zhen Lei The contents of the slab object may contain some magic words and other useful information that may be helpful in locating problems such as memory corruption and use-after-free. To avoid print flooding, dump up to "16 * sizeof(int) = 64" bytes centered on argument 'ojbect'. For example: slab kmalloc-64 start ffff4043802d8b40 pointer offset 24 size 64 [8b40]: 12345678 00000000 8092d000 ffff8000 [8b50]: 00101000 00000000 8199ee00 ffff4043 [8b60]: 00000000 00000000 00000000 00000100 [8b70]: 00000000 9abcdef0 a8744de4 ffffc7fe Signed-off-by: Zhen Lei --- mm/slab_common.c | 27 ++++++++++++++++++++++++--- 1 file changed, 24 insertions(+), 3 deletions(-) diff --git a/mm/slab_common.c b/mm/slab_common.c index ee6ed6dd7ba9fa5..3564e60a2584b12 100644 --- a/mm/slab_common.c +++ b/mm/slab_common.c @@ -553,7 +553,7 @@ static void kmem_obj_info(struct kmem_obj_info *kpp, void *object, struct slab * bool kmem_dump_obj(void *object) { char *cp = IS_ENABLED(CONFIG_MMU) ? "" : "/vmalloc"; - int i; + int i, object_size = 0; struct slab *slab; unsigned long ptroffset; struct kmem_obj_info kp = { }; @@ -580,12 +580,33 @@ bool kmem_dump_obj(void *object) ptroffset = ((char *)object - (char *)kp.kp_objp) - kp.kp_data_offset; pr_cont(" pointer offset %lu", ptroffset); } - if (kp.kp_slab_cache && kp.kp_slab_cache->object_size) - pr_cont(" size %u", kp.kp_slab_cache->object_size); + if (kp.kp_slab_cache && kp.kp_slab_cache->object_size) { + object_size = kp.kp_slab_cache->object_size; + pr_cont(" size %u", object_size); + } if (kp.kp_ret) pr_cont(" allocated at %pS\n", kp.kp_ret); else pr_cont("\n"); + + /* Dump a small piece of memory centered on 'object' */ + if (kp.kp_objp && object_size) { + void *p = object; + int dump_size = 64; + + p += dump_size / 2; + if (p > kp.kp_objp + object_size) + p = kp.kp_objp + object_size; + + p -= dump_size; + if (p < kp.kp_objp) + p = kp.kp_objp; + + dump_size = min(object_size, dump_size); + print_hex_dump(KERN_INFO, "", + DUMP_PREFIX_ADDRESS_LOW16, 16, 4, p, dump_size, false); + } + for (i = 0; i < ARRAY_SIZE(kp.kp_stack); i++) { if (!kp.kp_stack[i]) break; -- 2.34.1