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authorMiroslav Benes <mbenes@suse.cz>2019-09-04 16:10:05 +0200
committerMiroslav Benes <mbenes@suse.cz>2019-09-05 13:08:08 +0200
commit62b79910d8b20dab4f3345f5d3d58e45d47565e5 (patch)
tree12a506305d0c0fa6b59e282bf54d05d56b0ee6f3
parent5ab410a9916ebd9343d0e765bc2e99968a5541fb (diff)
ftrace: Fix NULL pointer dereference in t_probe_next()
(bsc#1149413).
-rw-r--r--patches.suse/ftrace-fix-null-pointer-dereference-in-t_probe_next.patch77
-rw-r--r--series.conf1
2 files changed, 78 insertions, 0 deletions
diff --git a/patches.suse/ftrace-fix-null-pointer-dereference-in-t_probe_next.patch b/patches.suse/ftrace-fix-null-pointer-dereference-in-t_probe_next.patch
new file mode 100644
index 0000000000..4505f4355b
--- /dev/null
+++ b/patches.suse/ftrace-fix-null-pointer-dereference-in-t_probe_next.patch
@@ -0,0 +1,77 @@
+From: "Naveen N. Rao" <naveen.n.rao@linux.vnet.ibm.com>
+Date: Thu, 4 Jul 2019 20:04:41 +0530
+Subject: ftrace: Fix NULL pointer dereference in t_probe_next()
+Git-commit: 7bd46644ea0f6021dc396a39a8bfd3a58f6f1f9f
+Patch-mainline: v5.3-rc7
+References: bsc#1149413
+
+LTP testsuite on powerpc results in the below crash:
+
+ Unable to handle kernel paging request for data at address 0x00000000
+ Faulting instruction address: 0xc00000000029d800
+ Oops: Kernel access of bad area, sig: 11 [#1]
+ LE SMP NR_CPUS=2048 NUMA PowerNV
+ ...
+ CPU: 68 PID: 96584 Comm: cat Kdump: loaded Tainted: G W
+ NIP: c00000000029d800 LR: c00000000029dac4 CTR: c0000000001e6ad0
+ REGS: c0002017fae8ba10 TRAP: 0300 Tainted: G W
+ MSR: 9000000000009033 <SF,HV,EE,ME,IR,DR,RI,LE> CR: 28022422 XER: 20040000
+ CFAR: c00000000029d90c DAR: 0000000000000000 DSISR: 40000000 IRQMASK: 0
+ ...
+ NIP [c00000000029d800] t_probe_next+0x60/0x180
+ LR [c00000000029dac4] t_mod_start+0x1a4/0x1f0
+ Call Trace:
+ [c0002017fae8bc90] [c000000000cdbc40] _cond_resched+0x10/0xb0 (unreliable)
+ [c0002017fae8bce0] [c0000000002a15b0] t_start+0xf0/0x1c0
+ [c0002017fae8bd30] [c0000000004ec2b4] seq_read+0x184/0x640
+ [c0002017fae8bdd0] [c0000000004a57bc] sys_read+0x10c/0x300
+ [c0002017fae8be30] [c00000000000b388] system_call+0x5c/0x70
+
+The test (ftrace_set_ftrace_filter.sh) is part of ftrace stress tests
+and the crash happens when the test does 'cat
+$TRACING_PATH/set_ftrace_filter'.
+
+The address points to the second line below, in t_probe_next(), where
+filter_hash is dereferenced:
+ hash = iter->probe->ops.func_hash->filter_hash;
+ size = 1 << hash->size_bits;
+
+This happens due to a race with register_ftrace_function_probe(). A new
+ftrace_func_probe is created and added into the func_probes list in
+trace_array under ftrace_lock. However, before initializing the filter,
+we drop ftrace_lock, and re-acquire it after acquiring regex_lock. If
+another process is trying to read set_ftrace_filter, it will be able to
+acquire ftrace_lock during this window and it will end up seeing a NULL
+filter_hash.
+
+Fix this by just checking for a NULL filter_hash in t_probe_next(). If
+the filter_hash is NULL, then this probe is just being added and we can
+simply return from here.
+
+Link: http://lkml.kernel.org/r/05e021f757625cbbb006fad41380323dbe4e3b43.1562249521.git.naveen.n.rao@linux.vnet.ibm.com
+
+Cc: stable@vger.kernel.org
+Fixes: 7b60f3d876156 ("ftrace: Dynamically create the probe ftrace_ops for the trace_array")
+Signed-off-by: Naveen N. Rao <naveen.n.rao@linux.vnet.ibm.com>
+Signed-off-by: Steven Rostedt (VMware) <rostedt@goodmis.org>
+Acked-by: Miroslav Benes <mbenes@suse.cz>
+---
+ kernel/trace/ftrace.c | 4 ++++
+ 1 file changed, 4 insertions(+)
+
+diff --git a/kernel/trace/ftrace.c b/kernel/trace/ftrace.c
+index eca34503f178..80beed2cf0da 100644
+--- a/kernel/trace/ftrace.c
++++ b/kernel/trace/ftrace.c
+@@ -3095,6 +3095,10 @@ t_probe_next(struct seq_file *m, loff_t *pos)
+ hnd = &iter->probe_entry->hlist;
+
+ hash = iter->probe->ops.func_hash->filter_hash;
++
++ if (!hash)
++ return NULL;
++
+ size = 1 << hash->size_bits;
+
+ retry:
+
diff --git a/series.conf b/series.conf
index 01805f69ff..82efae56e9 100644
--- a/series.conf
+++ b/series.conf
@@ -24157,6 +24157,7 @@
patches.suse/ALSA-seq-Fix-potential-concurrent-access-to-the-dele.patch
patches.suse/mmc-sdhci-of-at91-add-quirk-for-broken-HS200.patch
patches.suse/kvm-x86-don-t-update-rip-or-do-single-step-on-faulting-emulation
+ patches.suse/ftrace-fix-null-pointer-dereference-in-t_probe_next.patch
patches.suse/batman-adv-Only-read-OGM-tvlv_len-after-buffer-len-c.patch
patches.suse/batman-adv-Only-read-OGM2-tvlv_len-after-buffer-len-.patch
patches.suse/usb-host-xhci-rcar-Fix-typo-in-compatible-string-mat.patch