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[126.11.124.198]) by smtp.gmail.com with ESMTPSA id u17sm7212039pgf.8.2019.09.22.00.45.33 (version=TLS1_2 cipher=ECDHE-RSA-CHACHA20-POLY1305 bits=256/256); Sun, 22 Sep 2019 00:45:34 -0700 (PDT) Date: Sun, 22 Sep 2019 16:45:31 +0900 From: Takeshi Misawa To: Guillaume Nault , Paul Mackerras Cc: netdev@vger.kernel.org Subject: [PATCH net] ppp: Fix memory leak in ppp_write Message-ID: <20190922074531.GA1450@DESKTOP> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline User-Agent: Mutt/1.9.4 (2018-02-28) Sender: netdev-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: netdev@vger.kernel.org When ppp is closing, __ppp_xmit_process() failed to enqueue skb and skb allocated in ppp_write() is leaked. syzbot reported : BUG: memory leak unreferenced object 0xffff88812a17bc00 (size 224): comm "syz-executor673", pid 6952, jiffies 4294942888 (age 13.040s) hex dump (first 32 bytes): 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 ................ 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 ................ backtrace: [<00000000d110fff9>] kmemleak_alloc_recursive include/linux/kmemleak.h:43 [inline] [<00000000d110fff9>] slab_post_alloc_hook mm/slab.h:522 [inline] [<00000000d110fff9>] slab_alloc_node mm/slab.c:3262 [inline] [<00000000d110fff9>] kmem_cache_alloc_node+0x163/0x2f0 mm/slab.c:3574 [<000000002d616113>] __alloc_skb+0x6e/0x210 net/core/skbuff.c:197 [<000000000167fc45>] alloc_skb include/linux/skbuff.h:1055 [inline] [<000000000167fc45>] ppp_write+0x48/0x120 drivers/net/ppp/ppp_generic.c:502 [<000000009ab42c0b>] __vfs_write+0x43/0xa0 fs/read_write.c:494 [<00000000086b2e22>] vfs_write fs/read_write.c:558 [inline] [<00000000086b2e22>] vfs_write+0xee/0x210 fs/read_write.c:542 [<00000000a2b70ef9>] ksys_write+0x7c/0x130 fs/read_write.c:611 [<00000000ce5e0fdd>] __do_sys_write fs/read_write.c:623 [inline] [<00000000ce5e0fdd>] __se_sys_write fs/read_write.c:620 [inline] [<00000000ce5e0fdd>] __x64_sys_write+0x1e/0x30 fs/read_write.c:620 [<00000000d9d7b370>] do_syscall_64+0x76/0x1a0 arch/x86/entry/common.c:296 [<0000000006e6d506>] entry_SYSCALL_64_after_hwframe+0x44/0xa9 Fix this by freeing skb, if ppp is closing. Fixes: 6d066734e9f0 ("ppp: avoid loop in xmit recursion detection code") Reported-and-tested-by: syzbot+d9c8bf24e56416d7ce2c@syzkaller.appspotmail.com Signed-off-by: Takeshi Misawa --- Dear Guillaume Nault, Paul Mackerras syzbot reported memory leak in net/ppp. - memory leak in ppp_write I send a patch that passed syzbot reproducer test. Please consider this memory leak and patch. Regards. --- drivers/net/ppp/ppp_generic.c | 2 ++ 1 file changed, 2 insertions(+) diff --git a/drivers/net/ppp/ppp_generic.c b/drivers/net/ppp/ppp_generic.c index a30e41a56085..9a1b006904a7 100644 --- a/drivers/net/ppp/ppp_generic.c +++ b/drivers/net/ppp/ppp_generic.c @@ -1415,6 +1415,8 @@ static void __ppp_xmit_process(struct ppp *ppp, struct sk_buff *skb) netif_wake_queue(ppp->dev); else netif_stop_queue(ppp->dev); + } else { + kfree_skb(skb); } ppp_xmit_unlock(ppp); } -- 2.17.1