--- /dev/null
+From 372e0d01da71c84dcecf7028598a33813b0d5256 Mon Sep 17 00:00:00 2001
+From: "Steven Rostedt (VMware)" <rostedt@goodmis.org>
+Date: Fri, 30 Aug 2019 16:30:01 -0400
+Subject: ftrace: Check for empty hash and comment the race with registering probes
+
+From: Steven Rostedt (VMware) <rostedt@goodmis.org>
+
+commit 372e0d01da71c84dcecf7028598a33813b0d5256 upstream.
+
+The race between adding a function probe and reading the probes that exist
+is very subtle. It needs a comment. Also, the issue can also happen if the
+probe has has the EMPTY_HASH as its func_hash.
+
+Cc: stable@vger.kernel.org
+Fixes: 7b60f3d876156 ("ftrace: Dynamically create the probe ftrace_ops for the trace_array")
+Signed-off-by: Steven Rostedt (VMware) <rostedt@goodmis.org>
+Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
+
+---
+ kernel/trace/ftrace.c | 10 +++++++++-
+ 1 file changed, 9 insertions(+), 1 deletion(-)
+
+--- a/kernel/trace/ftrace.c
++++ b/kernel/trace/ftrace.c
+@@ -3185,7 +3185,11 @@ t_probe_next(struct seq_file *m, loff_t
+
+ hash = iter->probe->ops.func_hash->filter_hash;
+
+- if (!hash)
++ /*
++ * A probe being registered may temporarily have an empty hash
++ * and it's at the end of the func_probes list.
++ */
++ if (!hash || hash == EMPTY_HASH)
+ return NULL;
+
+ size = 1 << hash->size_bits;
+@@ -4384,6 +4388,10 @@ register_ftrace_function_probe(char *glo
+
+ mutex_unlock(&ftrace_lock);
+
++ /*
++ * Note, there's a small window here that the func_hash->filter_hash
++ * may be NULL or empty. Need to be carefule when reading the loop.
++ */
+ mutex_lock(&probe->ops.func_hash->regex_lock);
+
+ orig_hash = &probe->ops.func_hash->filter_hash;
--- /dev/null
+From 5b0022dd32b7c2e15edf1827ba80aa1407edf9ff Mon Sep 17 00:00:00 2001
+From: "Naveen N. Rao" <naveen.n.rao@linux.vnet.ibm.com>
+Date: Thu, 4 Jul 2019 20:04:42 +0530
+Subject: ftrace: Check for successful allocation of hash
+
+From: Naveen N. Rao <naveen.n.rao@linux.vnet.ibm.com>
+
+commit 5b0022dd32b7c2e15edf1827ba80aa1407edf9ff upstream.
+
+In register_ftrace_function_probe(), we are not checking the return
+value of alloc_and_copy_ftrace_hash(). The subsequent call to
+ftrace_match_records() may end up dereferencing the same. Add a check to
+ensure this doesn't happen.
+
+Link: http://lkml.kernel.org/r/26e92574f25ad23e7cafa3cf5f7a819de1832cbe.1562249521.git.naveen.n.rao@linux.vnet.ibm.com
+
+Cc: stable@vger.kernel.org
+Fixes: 1ec3a81a0cf42 ("ftrace: Have each function probe use its own ftrace_ops")
+Signed-off-by: Naveen N. Rao <naveen.n.rao@linux.vnet.ibm.com>
+Signed-off-by: Steven Rostedt (VMware) <rostedt@goodmis.org>
+Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
+
+---
+ kernel/trace/ftrace.c | 5 +++++
+ 1 file changed, 5 insertions(+)
+
+--- a/kernel/trace/ftrace.c
++++ b/kernel/trace/ftrace.c
+@@ -4390,6 +4390,11 @@ register_ftrace_function_probe(char *glo
+ old_hash = *orig_hash;
+ hash = alloc_and_copy_ftrace_hash(FTRACE_HASH_DEFAULT_BITS, old_hash);
+
++ if (!hash) {
++ ret = -ENOMEM;
++ goto out;
++ }
++
+ ret = ftrace_match_records(hash, glob, strlen(glob));
+
+ /* Nothing found? */
--- /dev/null
+From 7bd46644ea0f6021dc396a39a8bfd3a58f6f1f9f Mon Sep 17 00:00:00 2001
+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()
+
+From: Naveen N. Rao <naveen.n.rao@linux.vnet.ibm.com>
+
+commit 7bd46644ea0f6021dc396a39a8bfd3a58f6f1f9f upstream.
+
+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>
+Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
+
+---
+ kernel/trace/ftrace.c | 4 ++++
+ 1 file changed, 4 insertions(+)
+
+--- a/kernel/trace/ftrace.c
++++ b/kernel/trace/ftrace.c
+@@ -3184,6 +3184,10 @@ t_probe_next(struct seq_file *m, loff_t
+ hnd = &iter->probe_entry->hlist;
+
+ hash = iter->probe->ops.func_hash->filter_hash;
++
++ if (!hash)
++ return NULL;
++
+ size = 1 << hash->size_bits;
+
+ retry:
kvm-x86-don-t-update-rip-or-do-single-step-on-faulting-emulation.patch
x86-apic-do-not-initialize-ldr-and-dfr-for-bigsmp.patch
x86-apic-include-the-ldr-when-clearing-out-apic-registers.patch
+ftrace-fix-null-pointer-dereference-in-t_probe_next.patch
+ftrace-check-for-successful-allocation-of-hash.patch
+ftrace-check-for-empty-hash-and-comment-the-race-with-registering-probes.patch
projects / thirdparty / kernel / stable-queue.git / commitdiff
