linux-kernel - [PATCH] dm-region-hash: Fix a missing-check bug in __rh

lists.openwall.net		lists / announce owl-users owl-dev john-users john-dev passwdqc-users yescrypt popa3d-users / oss-security kernel-hardening musl sabotage tlsify passwords / crypt-dev xvendor / Bugtraq Full-Disclosure linux-kernel linux-netdev linux-ext4 linux-hardening linux-cve-announce PHC
Open Source and information security mailing list archives

Hash Suite: Windows password security audit tool. GUI, reports in PDF.

[<prev] [next>] [thread-next>] [day] [month] [year] [list]

Message-ID: <20190524031248.GA6295@zhanggen-UX430UQ>
Date:   Fri, 24 May 2019 11:12:48 +0800
From:   Gen Zhang <blackgod016574@...il.com>
To:     agk@...hat.com, snitzer@...hat.com, dm-devel@...hat.com
Cc:     linux-kernel@...r.kernel.org
Subject: [PATCH] dm-region-hash: Fix a missing-check bug in __rh_alloc()

In function __rh_alloc(), the pointer nreg is allocated a memory space
via kmalloc(). And it is used in the following codes. However, when 
there is a memory allocation error, kmalloc() fails. Thus null pointer
dereference may happen. And it will cause the kernel to crash. Therefore,
we should check the return value and handle the error.
Further, in __rh_find(), we should also check the return value and
handle the error.

Signed-off-by: Gen Zhang <blackgod016574@...il.com>

---
diff --git a/drivers/md/dm-region-hash.c b/drivers/md/dm-region-hash.c
index 1f76045..2fa1641 100644
--- a/drivers/md/dm-region-hash.c
+++ b/drivers/md/dm-region-hash.c
@@ -290,8 +290,11 @@ static struct dm_region *__rh_alloc(struct dm_region_hash *rh, region_t region)
 	struct dm_region *reg, *nreg;
 
 	nreg = mempool_alloc(&rh->region_pool, GFP_ATOMIC);
-	if (unlikely(!nreg))
+	if (unlikely(!nreg)) {
 		nreg = kmalloc(sizeof(*nreg), GFP_NOIO | __GFP_NOFAIL);
+		if (!nreg)
+			return NULL;
+	}
 
 	nreg->state = rh->log->type->in_sync(rh->log, region, 1) ?
 		      DM_RH_CLEAN : DM_RH_NOSYNC;
@@ -329,6 +332,8 @@ static struct dm_region *__rh_find(struct dm_region_hash *rh, region_t region)
 	if (!reg) {
 		read_unlock(&rh->hash_lock);
 		reg = __rh_alloc(rh, region);
+		if (!reg)
+			return NULL;
 		read_lock(&rh->hash_lock);
 	}
 
---