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[128.101.215.112]) by smtp.gmail.com with ESMTPSA id c14sm10675549ild.41.2020.08.09.15.14.59 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Sun, 09 Aug 2020 15:14:59 -0700 (PDT) From: James Bond To: jameslouisebond@gmail.com Cc: Greg Kroah-Hartman , Jiri Slaby , Andrew Morton , Kees Cook , Michel Lespinasse , Vlastimil Babka , Denis Efremov , linux-kernel@vger.kernel.org Subject: [PATCH] tty/vt: fix a memory leak in con_insert_unipair Date: Sun, 9 Aug 2020 17:14:52 -0500 Message-Id: <20200809221453.10235-1-jameslouisebond@gmail.com> X-Mailer: git-send-email 2.17.1 Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Syzkaller find a memory leak in con_insert_unipair: BUG: memory leak unreferenced object 0xffff88804893d100 (size 256): comm "syz-executor.3", pid 16154, jiffies 4295043307 (age 2392.340s) hex dump (first 32 bytes): 80 af 88 4e 80 88 ff ff 00 a8 88 4e 80 88 ff ff ...N.......N.... 80 ad 88 4e 80 88 ff ff 00 aa 88 4e 80 88 ff ff ...N.......N.... backtrace: [<00000000f76ff1de>] kmalloc include/linux/slab.h:555 [inline] [<00000000f76ff1de>] kmalloc_array include/linux/slab.h:596 [inline] [<00000000f76ff1de>] con_insert_unipair+0x9e/0x1a0 drivers/tty/vt/consolemap.c:482 [<000000002f1ad7da>] con_set_unimap+0x244/0x2a0 drivers/tty/vt/consolemap.c:595 [<0000000046ccb106>] do_unimap_ioctl drivers/tty/vt/vt_ioctl.c:297 [inline] [<0000000046ccb106>] vt_ioctl+0x863/0x12f0 drivers/tty/vt/vt_ioctl.c:1018 [<00000000db1577ff>] tty_ioctl+0x4cd/0xa30 drivers/tty/tty_io.c:2656 [<00000000e5cdf5ed>] vfs_ioctl fs/ioctl.c:48 [inline] [<00000000e5cdf5ed>] ksys_ioctl+0xa6/0xd0 fs/ioctl.c:753 [<00000000fb4aa12c>] __do_sys_ioctl fs/ioctl.c:762 [inline] [<00000000fb4aa12c>] __se_sys_ioctl fs/ioctl.c:760 [inline] [<00000000fb4aa12c>] __x64_sys_ioctl+0x1a/0x20 fs/ioctl.c:760 [<00000000f561f260>] do_syscall_64+0x4c/0xe0 arch/x86/entry/common.c:384 [<0000000056206928>] entry_SYSCALL_64_after_hwframe+0x44/0xa9 BUG: leak checking failed To fix this issue, we need to release the pointer p1 when the call of the function kmalloc_array fail. Signed-off-by: James Bond --- drivers/tty/vt/consolemap.c | 5 ++++- 1 file changed, 4 insertions(+), 1 deletion(-) diff --git a/drivers/tty/vt/consolemap.c b/drivers/tty/vt/consolemap.c index 5947b54d92be..1e8d06c32ca1 100644 --- a/drivers/tty/vt/consolemap.c +++ b/drivers/tty/vt/consolemap.c @@ -489,7 +489,10 @@ con_insert_unipair(struct uni_pagedir *p, u_short unicode, u_short fontpos) p2 = p1[n = (unicode >> 6) & 0x1f]; if (!p2) { p2 = p1[n] = kmalloc_array(64, sizeof(u16), GFP_KERNEL); - if (!p2) return -ENOMEM; + if (!p2) { + kfree(p1); + return -ENOMEM; + } memset(p2, 0xff, 64*sizeof(u16)); /* No glyphs for the characters (yet) */ } -- 2.17.1