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[153.205.136.188]) by smtp.gmail.com with ESMTPSA id o13sm3113636pfh.23.2019.06.14.00.40.57 (version=TLS1_3 cipher=AEAD-AES256-GCM-SHA384 bits=256/256); Fri, 14 Jun 2019 00:40:59 -0700 (PDT) From: Eiichi Tsukata To: rostedt@goodmis.org, mingo@redhat.com, srikar@linux.vnet.ibm.com, mhiramat@kernel.org, linux-kernel@vger.kernel.org Cc: Eiichi Tsukata Subject: [PATCH 1/2] tracing/uprobe: Fix NULL pointer dereference in trace_uprobe_create() Date: Fri, 14 Jun 2019 16:40:25 +0900 Message-Id: <20190614074026.8045-1-devel@etsukata.com> X-Mailer: git-send-email 2.21.0 MIME-Version: 1.0 Content-Transfer-Encoding: 8bit Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Just like the case of commit 8b05a3a7503c ("tracing/kprobes: Fix NULL pointer dereference in trace_kprobe_create()"), writing an incorrectly formatted string to uprobe_events can trigger NULL pointer dereference. Reporeducer: # echo r > /sys/kernel/debug/tracing/uprobe_events dmesg: BUG: kernel NULL pointer dereference, address: 0000000000000000 #PF: supervisor read access in kernel mode #PF: error_code(0x0000) - not-present page PGD 8000000079d12067 P4D 8000000079d12067 PUD 7b7ab067 PMD 0 Oops: 0000 [#1] PREEMPT SMP PTI CPU: 0 PID: 1903 Comm: bash Not tainted 5.2.0-rc3+ #15 Hardware name: QEMU Standard PC (i440FX + PIIX, 1996), BIOS 1.12.0-2.fc30 04/01/2014 RIP: 0010:strchr+0x0/0x30 Code: c0 eb 0d 84 c9 74 18 48 83 c0 01 48 39 d0 74 0f 0f b6 0c 07 3a 0c 06 74 ea 19 c0 83 c8 01 c3 31 c0 c3 0f 1f 84 00 00 00 00 00 <0f> b6 07 89 f2 40 38 f0 75 0e eb 13 0f b6 47 01 48 83 c RSP: 0018:ffffb55fc0403d10 EFLAGS: 00010293 RAX: ffff993ffb793400 RBX: 0000000000000000 RCX: ffffffffa4852625 RDX: 0000000000000000 RSI: 000000000000002f RDI: 0000000000000000 RBP: ffffb55fc0403dd0 R08: ffff993ffb793400 R09: 0000000000000000 R10: 0000000000000000 R11: 0000000000000000 R12: 0000000000000000 R13: ffff993ff9cc1668 R14: 0000000000000001 R15: 0000000000000000 FS: 00007f30c5147700(0000) GS:ffff993ffda00000(0000) knlGS:0000000000000000 CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033 CR2: 0000000000000000 CR3: 000000007b628000 CR4: 00000000000006f0 Call Trace: trace_uprobe_create+0xe6/0xb10 ? __kmalloc_track_caller+0xe6/0x1c0 ? __kmalloc+0xf0/0x1d0 ? trace_uprobe_create+0xb10/0xb10 create_or_delete_trace_uprobe+0x35/0x90 ? trace_uprobe_create+0xb10/0xb10 trace_run_command+0x9c/0xb0 trace_parse_run_command+0xf9/0x1eb ? probes_open+0x80/0x80 __vfs_write+0x43/0x90 vfs_write+0x14a/0x2a0 ksys_write+0xa2/0x170 do_syscall_64+0x7f/0x200 entry_SYSCALL_64_after_hwframe+0x49/0xbe Fixes: 0597c49c69d5 ("tracing/uprobes: Use dyn_event framework for uprobe events") Signed-off-by: Eiichi Tsukata --- kernel/trace/trace_uprobe.c | 13 ++++++++++--- 1 file changed, 10 insertions(+), 3 deletions(-) diff --git a/kernel/trace/trace_uprobe.c b/kernel/trace/trace_uprobe.c index 0d60d6856de5..7dc8ee55cf84 100644 --- a/kernel/trace/trace_uprobe.c +++ b/kernel/trace/trace_uprobe.c @@ -443,10 +443,17 @@ static int trace_uprobe_create(int argc, const char **argv) ret = 0; ref_ctr_offset = 0; - /* argc must be >= 1 */ - if (argv[0][0] == 'r') + switch (argv[0][0]) { + case 'r': is_return = true; - else if (argv[0][0] != 'p' || argc < 2) + break; + case 'p': + break; + default: + return -ECANCELED; + } + + if (argc < 2) return -ECANCELED; if (argv[0][1] == ':') -- 2.21.0