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Sat, 12 Nov 2022 18:33:01 +0800 From: Liu Shixin To: Christoph Lameter , Pekka Enberg , "David Rientjes" , Joonsoo Kim , "Andrew Morton" , Vlastimil Babka , "Roman Gushchin" , Hyeonggon Yoo <42.hyeyoo@gmail.com> CC: , , Liu Shixin Subject: [PATCH v3 3/3] mm/slub: Fix memory leak of kobj->name in sysfs_slab_add() Date: Sat, 12 Nov 2022 19:20:55 +0800 Message-ID: <20221112112055.1111078-4-liushixin2@huawei.com> X-Mailer: git-send-email 2.25.1 In-Reply-To: <20221112112055.1111078-1-liushixin2@huawei.com> References: <20221112112055.1111078-1-liushixin2@huawei.com> MIME-Version: 1.0 X-Originating-IP: [10.175.113.32] X-ClientProxiedBy: dggems703-chm.china.huawei.com (10.3.19.180) To dggpemm100009.china.huawei.com (7.185.36.113) X-CFilter-Loop: Reflected ARC-Seal: i=1; s=arc-20220608; d=hostedemail.com; t=1668249186; a=rsa-sha256; cv=none; b=OhE6o+7xfq2WSBCXO3GBFeWyWErOCP+Su1MjCEYuxLU9qCmDEpaV3xg5UAx8WrYWo3qH+y SNCYsUZHtpA93mb2zsnSINcyVW15LApp4kp7IkfpZ52/IXoAAx4/95kZ1ymCStDbt+LocY jUad5SbjXtOSCXMfNngsuxrgSLaQGZM= ARC-Authentication-Results: i=1; imf06.hostedemail.com; dkim=none; dmarc=pass (policy=quarantine) header.from=huawei.com; spf=pass (imf06.hostedemail.com: domain of liushixin2@huawei.com designates 45.249.212.255 as permitted sender) smtp.mailfrom=liushixin2@huawei.com ARC-Message-Signature: i=1; a=rsa-sha256; c=relaxed/relaxed; d=hostedemail.com; s=arc-20220608; t=1668249186; h=from:from:sender:reply-to:subject:subject:date:date: message-id:message-id:to:to:cc:cc:mime-version:mime-version: content-type:content-type: content-transfer-encoding:content-transfer-encoding: in-reply-to:in-reply-to:references:references; bh=mtV6wkCFPXYCWtk1Ao0m893pEu81mkEMvcctfZmwBd4=; b=S1JzXwGSoYNvQ5I1kO2yczkiBtKkqK8Dn6HgTG6JaObIuJvRzD7L+xvJzO+Vl3jSrakJHq u03Ae3Kh0Kns9vI2lagsYhgSJ4ShdCehccIP3vwPnlTTuMbsGaLsY6QSnImN1Ajbr3XQlU o+mM4t8RnzdZhqnHlt/7C0mnamtDDXQ= X-Rspamd-Queue-Id: BB920180007 Authentication-Results: imf06.hostedemail.com; dkim=none; dmarc=pass (policy=quarantine) header.from=huawei.com; spf=pass (imf06.hostedemail.com: domain of liushixin2@huawei.com designates 45.249.212.255 as permitted sender) smtp.mailfrom=liushixin2@huawei.com X-Rspam-User: X-Rspamd-Server: rspam01 X-Stat-Signature: xyq31knjzosgsaytmoxb6uokbdye3c5k X-HE-Tag: 1668249185-339876 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: There is a memory leak of kobj->name in sysfs_slab_add(): unreferenced object 0xffff88817e446440 (size 32): comm "insmod", pid 4085, jiffies 4296564501 (age 126.272s) hex dump (first 32 bytes): 75 62 69 66 73 5f 69 6e 6f 64 65 5f 73 6c 61 62 ubifs_inode_slab 00 65 44 7e 81 88 ff ff 00 00 00 00 00 00 00 00 .eD~............ backtrace: [<000000005b30fbbd>] __kmalloc_node_track_caller+0x4e/0x150 [<000000002f70da0c>] kstrdup_const+0x4b/0x80 [<00000000c6712c61>] kobject_set_name_vargs+0x2f/0xb0 [<00000000b151218e>] kobject_init_and_add+0xb0/0x120 [<00000000e56a4cf5>] sysfs_slab_add+0x17d/0x220 [<000000009326fd57>] __kmem_cache_create+0x406/0x590 [<00000000dde33cff>] kmem_cache_create_usercopy+0x1fc/0x300 [<00000000fe90cedb>] kmem_cache_create+0x12/0x20 [<000000007a6531c8>] 0xffffffffa02d802d [<000000000e3b13c7>] do_one_initcall+0x87/0x2a0 [<00000000995ecdcf>] do_init_module+0xdf/0x320 [<000000008821941f>] load_module+0x2f98/0x3330 [<00000000ef51efa4>] __do_sys_finit_module+0x113/0x1b0 [<000000009339fbce>] do_syscall_64+0x35/0x80 [<000000006b7f2033>] entry_SYSCALL_64_after_hwframe+0x46/0xb0 Following the rules stated in the comment for kobject_init_and_add(): If this function returns an error, kobject_put() must be called to properly clean up the memory associated with the object. kobject_put() is more appropriate for error handling after kobject_init(). And we can use this function to solve this problem. For the cache created early, the related sysfs_slab_add() is called in slab_sysfs_init(). Skip free these kmem_cache since they are important for system. Keep them working without sysfs. Fixes: 80da026a8e5d ("mm/slub: fix slab double-free in case of duplicate sysfs filename") Signed-off-by: Liu Shixin --- include/linux/slub_def.h | 4 ++-- mm/slab_common.c | 6 ++---- mm/slub.c | 21 +++++++++++++++++---- 3 files changed, 21 insertions(+), 10 deletions(-) diff --git a/include/linux/slub_def.h b/include/linux/slub_def.h index 26d56c4c74d1..90c3e06b77b1 100644 --- a/include/linux/slub_def.h +++ b/include/linux/slub_def.h @@ -144,11 +144,11 @@ struct kmem_cache { #ifdef CONFIG_SYSFS #define SLAB_SUPPORTS_SYSFS -int sysfs_slab_add(struct kmem_cache *); +int sysfs_slab_add(struct kmem_cache *, bool); void sysfs_slab_unlink(struct kmem_cache *); void sysfs_slab_release(struct kmem_cache *); #else -static inline int sysfs_slab_add(struct kmem_cache *s) +static inline int sysfs_slab_add(struct kmem_cache *s, bool free_slab) { return 0; } diff --git a/mm/slab_common.c b/mm/slab_common.c index 55e2cf064dfe..30808a1d1b32 100644 --- a/mm/slab_common.c +++ b/mm/slab_common.c @@ -237,11 +237,9 @@ static struct kmem_cache *create_cache(const char *name, #ifdef SLAB_SUPPORTS_SYSFS /* Mutex is not taken during early boot */ if (slab_state >= FULL) { - err = sysfs_slab_add(s); - if (err) { - slab_kmem_cache_release(s); + err = sysfs_slab_add(s, true); + if (err) return ERR_PTR(err); - } debugfs_slab_add(s); } #endif diff --git a/mm/slub.c b/mm/slub.c index a1ad759753ce..06a3223fc833 100644 --- a/mm/slub.c +++ b/mm/slub.c @@ -5881,7 +5881,7 @@ static char *create_unique_id(struct kmem_cache *s) return name; } -int sysfs_slab_add(struct kmem_cache *s) +int sysfs_slab_add(struct kmem_cache *s, bool free_slab) { int err; const char *name; @@ -5911,14 +5911,17 @@ int sysfs_slab_add(struct kmem_cache *s) * for the symlinks. */ name = create_unique_id(s); - if (IS_ERR(name)) + if (IS_ERR(name)) { + if (free_slab) + slab_kmem_cache_release(s); return PTR_ERR(name); + } } s->kobj.kset = kset; err = kobject_init_and_add(&s->kobj, &slab_ktype, NULL, "%s", name); if (err) - goto out; + goto out_put_kobj; err = sysfs_create_group(&s->kobj, &slab_attr_group); if (err) @@ -5934,6 +5937,16 @@ int sysfs_slab_add(struct kmem_cache *s) return err; out_del_kobj: kobject_del(&s->kobj); +out_put_kobj: + /* + * Skip free kmem_cache that create early since they are important + * for system. Keep them working without sysfs. Only free name + * for this case. + */ + if (free_slab) + kobject_put(&s->kobj); + else + kfree_const(&s->kobj.name); goto out; } @@ -6002,7 +6015,7 @@ static int __init slab_sysfs_init(void) slab_state = FULL; list_for_each_entry(s, &slab_caches, list) { - err = sysfs_slab_add(s); + err = sysfs_slab_add(s, false); if (err) pr_err("SLUB: Unable to add boot slab %s to sysfs\n", s->name);