* [PATCH] ftrace: fix NULL pointer dereference in free_ftrace_func_mapper()
@ 2019-06-06 3:17 Wei Li
2019-06-14 21:40 ` Steven Rostedt
0 siblings, 1 reply; 2+ messages in thread
From: Wei Li @ 2019-06-06 3:17 UTC (permalink / raw)
To: rostedt, mingo; +Cc: huawei.libin, linux-kernel
The mapper may be NULL when called from register_ftrace_function_probe()
with probe->data == NULL.
This issue can be reproduced as follow (it may be coverd by compiler
optimization sometime):
/ # cat /sys/kernel/debug/tracing/set_ftrace_filter
#### all functions enabled ####
/ # echo foo_bar:dump > /sys/kernel/debug/tracing/set_ftrace_filter
[ 206.949100] Unable to handle kernel NULL pointer dereference at virtual address 0000000000000000
[ 206.952402] Mem abort info:
[ 206.952819] ESR = 0x96000006
[ 206.955326] Exception class = DABT (current EL), IL = 32 bits
[ 206.955844] SET = 0, FnV = 0
[ 206.956272] EA = 0, S1PTW = 0
[ 206.956652] Data abort info:
[ 206.957320] ISV = 0, ISS = 0x00000006
[ 206.959271] CM = 0, WnR = 0
[ 206.959938] user pgtable: 4k pages, 48-bit VAs, pgdp=0000000419f3a000
[ 206.960483] [0000000000000000] pgd=0000000411a87003, pud=0000000411a83003, pmd=0000000000000000
[ 206.964953] Internal error: Oops: 96000006 [#1] SMP
[ 206.971122] Dumping ftrace buffer:
[ 206.973677] (ftrace buffer empty)
[ 206.975258] Modules linked in:
[ 206.976631] Process sh (pid: 281, stack limit = 0x(____ptrval____))
[ 206.978449] CPU: 10 PID: 281 Comm: sh Not tainted 5.2.0-rc1+ #17
[ 206.978955] Hardware name: linux,dummy-virt (DT)
[ 206.979883] pstate: 60000005 (nZCv daif -PAN -UAO)
[ 206.980499] pc : free_ftrace_func_mapper+0x2c/0x118
[ 206.980874] lr : ftrace_count_free+0x68/0x80
[ 206.982539] sp : ffff0000182f3ab0
[ 206.983102] x29: ffff0000182f3ab0 x28: ffff8003d0ec1700
[ 206.983632] x27: ffff000013054b40 x26: 0000000000000001
[ 206.984000] x25: ffff00001385f000 x24: 0000000000000000
[ 206.984394] x23: ffff000013453000 x22: ffff000013054000
[ 206.984775] x21: 0000000000000000 x20: ffff00001385fe28
[ 206.986575] x19: ffff000013872c30 x18: 0000000000000000
[ 206.987111] x17: 0000000000000000 x16: 0000000000000000
[ 206.987491] x15: ffffffffffffffb0 x14: 0000000000000000
[ 206.987850] x13: 000000000017430e x12: 0000000000000580
[ 206.988251] x11: 0000000000000000 x10: cccccccccccccccc
[ 206.988740] x9 : 0000000000000000 x8 : ffff000013917550
[ 206.990198] x7 : ffff000012fac2e8 x6 : ffff000012fac000
[ 206.991008] x5 : ffff0000103da588 x4 : 0000000000000001
[ 206.991395] x3 : 0000000000000001 x2 : ffff000013872a28
[ 206.991771] x1 : 0000000000000000 x0 : 0000000000000000
[ 206.992557] Call trace:
[ 206.993101] free_ftrace_func_mapper+0x2c/0x118
[ 206.994827] ftrace_count_free+0x68/0x80
[ 206.995238] release_probe+0xfc/0x1d0
[ 206.995555] register_ftrace_function_probe+0x4a8/0x868
[ 206.995923] ftrace_trace_probe_callback.isra.4+0xb8/0x180
[ 206.996330] ftrace_dump_callback+0x50/0x70
[ 206.996663] ftrace_regex_write.isra.29+0x290/0x3a8
[ 206.997157] ftrace_filter_write+0x44/0x60
[ 206.998971] __vfs_write+0x64/0xf0
[ 206.999285] vfs_write+0x14c/0x2f0
[ 206.999591] ksys_write+0xbc/0x1b0
[ 206.999888] __arm64_sys_write+0x3c/0x58
[ 207.000246] el0_svc_common.constprop.0+0x408/0x5f0
[ 207.000607] el0_svc_handler+0x144/0x1c8
[ 207.000916] el0_svc+0x8/0xc
[ 207.003699] Code: aa0003f8 a9025bf5 aa0103f5 f946ea80 (f9400303)
[ 207.008388] ---[ end trace 7b6d11b5f542bdf1 ]---
[ 207.010126] Kernel panic - not syncing: Fatal exception
[ 207.011322] SMP: stopping secondary CPUs
[ 207.013956] Dumping ftrace buffer:
[ 207.014595] (ftrace buffer empty)
[ 207.015632] Kernel Offset: disabled
[ 207.017187] CPU features: 0x002,20006008
[ 207.017985] Memory Limit: none
[ 207.019825] ---[ end Kernel panic - not syncing: Fatal exception ]---
Signed-off-by: Wei Li <liwei391@huawei.com>
---
kernel/trace/ftrace.c | 7 +++++--
1 file changed, 5 insertions(+), 2 deletions(-)
diff --git a/kernel/trace/ftrace.c b/kernel/trace/ftrace.c
index a12aff849c04..7e2488da69ac 100644
--- a/kernel/trace/ftrace.c
+++ b/kernel/trace/ftrace.c
@@ -4221,10 +4221,13 @@ void free_ftrace_func_mapper(struct ftrace_func_mapper *mapper,
struct ftrace_func_entry *entry;
struct ftrace_func_map *map;
struct hlist_head *hhd;
- int size = 1 << mapper->hash.size_bits;
- int i;
+ int size, i;
+
+ if (!mapper)
+ return;
if (free_func && mapper->hash.count) {
+ size = 1 << mapper->hash.size_bits;
for (i = 0; i < size; i++) {
hhd = &mapper->hash.buckets[i];
hlist_for_each_entry(entry, hhd, hlist) {
--
2.17.1
^ permalink raw reply related [flat|nested] 2+ messages in thread
* Re: [PATCH] ftrace: fix NULL pointer dereference in free_ftrace_func_mapper()
2019-06-06 3:17 [PATCH] ftrace: fix NULL pointer dereference in free_ftrace_func_mapper() Wei Li
@ 2019-06-14 21:40 ` Steven Rostedt
0 siblings, 0 replies; 2+ messages in thread
From: Steven Rostedt @ 2019-06-14 21:40 UTC (permalink / raw)
To: Wei Li; +Cc: mingo, huawei.libin, linux-kernel
On Thu, 6 Jun 2019 11:17:54 +0800
Wei Li <liwei391@huawei.com> wrote:
> The mapper may be NULL when called from register_ftrace_function_probe()
> with probe->data == NULL.
>
> This issue can be reproduced as follow (it may be coverd by compiler
> optimization sometime):
>
> / # cat /sys/kernel/debug/tracing/set_ftrace_filter
I'm not able to reproduce this, but I have nothing against the patch.
It seems like a sane test. We can probably remove all the:
if (!mapper)
return;
before callers of this function then.
I'll apply this for my next push to Linus.
-- Steve
> #### all functions enabled ####
> / # echo foo_bar:dump > /sys/kernel/debug/tracing/set_ftrace_filter
> [ 206.949100] Unable to handle kernel NULL pointer dereference at virtual address 0000000000000000
> [ 206.952402] Mem abort info:
> [ 206.952819] ESR = 0x96000006
> [ 206.955326] Exception class = DABT (current EL), IL = 32 bits
> [ 206.955844] SET = 0, FnV = 0
> [ 206.956272] EA = 0, S1PTW = 0
> [ 206.956652] Data abort info:
> [ 206.957320] ISV = 0, ISS = 0x00000006
> [ 206.959271] CM = 0, WnR = 0
> [ 206.959938] user pgtable: 4k pages, 48-bit VAs, pgdp=0000000419f3a000
> [ 206.960483] [0000000000000000] pgd=0000000411a87003, pud=0000000411a83003, pmd=0000000000000000
> [ 206.964953] Internal error: Oops: 96000006 [#1] SMP
> [ 206.971122] Dumping ftrace buffer:
> [ 206.973677] (ftrace buffer empty)
> [ 206.975258] Modules linked in:
> [ 206.976631] Process sh (pid: 281, stack limit = 0x(____ptrval____))
> [ 206.978449] CPU: 10 PID: 281 Comm: sh Not tainted 5.2.0-rc1+ #17
> [ 206.978955] Hardware name: linux,dummy-virt (DT)
> [ 206.979883] pstate: 60000005 (nZCv daif -PAN -UAO)
> [ 206.980499] pc : free_ftrace_func_mapper+0x2c/0x118
> [ 206.980874] lr : ftrace_count_free+0x68/0x80
> [ 206.982539] sp : ffff0000182f3ab0
> [ 206.983102] x29: ffff0000182f3ab0 x28: ffff8003d0ec1700
> [ 206.983632] x27: ffff000013054b40 x26: 0000000000000001
> [ 206.984000] x25: ffff00001385f000 x24: 0000000000000000
> [ 206.984394] x23: ffff000013453000 x22: ffff000013054000
> [ 206.984775] x21: 0000000000000000 x20: ffff00001385fe28
> [ 206.986575] x19: ffff000013872c30 x18: 0000000000000000
> [ 206.987111] x17: 0000000000000000 x16: 0000000000000000
> [ 206.987491] x15: ffffffffffffffb0 x14: 0000000000000000
> [ 206.987850] x13: 000000000017430e x12: 0000000000000580
> [ 206.988251] x11: 0000000000000000 x10: cccccccccccccccc
> [ 206.988740] x9 : 0000000000000000 x8 : ffff000013917550
> [ 206.990198] x7 : ffff000012fac2e8 x6 : ffff000012fac000
> [ 206.991008] x5 : ffff0000103da588 x4 : 0000000000000001
> [ 206.991395] x3 : 0000000000000001 x2 : ffff000013872a28
> [ 206.991771] x1 : 0000000000000000 x0 : 0000000000000000
> [ 206.992557] Call trace:
> [ 206.993101] free_ftrace_func_mapper+0x2c/0x118
> [ 206.994827] ftrace_count_free+0x68/0x80
> [ 206.995238] release_probe+0xfc/0x1d0
> [ 206.995555] register_ftrace_function_probe+0x4a8/0x868
> [ 206.995923] ftrace_trace_probe_callback.isra.4+0xb8/0x180
> [ 206.996330] ftrace_dump_callback+0x50/0x70
> [ 206.996663] ftrace_regex_write.isra.29+0x290/0x3a8
> [ 206.997157] ftrace_filter_write+0x44/0x60
> [ 206.998971] __vfs_write+0x64/0xf0
> [ 206.999285] vfs_write+0x14c/0x2f0
> [ 206.999591] ksys_write+0xbc/0x1b0
> [ 206.999888] __arm64_sys_write+0x3c/0x58
> [ 207.000246] el0_svc_common.constprop.0+0x408/0x5f0
> [ 207.000607] el0_svc_handler+0x144/0x1c8
> [ 207.000916] el0_svc+0x8/0xc
> [ 207.003699] Code: aa0003f8 a9025bf5 aa0103f5 f946ea80 (f9400303)
> [ 207.008388] ---[ end trace 7b6d11b5f542bdf1 ]---
> [ 207.010126] Kernel panic - not syncing: Fatal exception
> [ 207.011322] SMP: stopping secondary CPUs
> [ 207.013956] Dumping ftrace buffer:
> [ 207.014595] (ftrace buffer empty)
> [ 207.015632] Kernel Offset: disabled
> [ 207.017187] CPU features: 0x002,20006008
> [ 207.017985] Memory Limit: none
> [ 207.019825] ---[ end Kernel panic - not syncing: Fatal exception ]---
>
> Signed-off-by: Wei Li <liwei391@huawei.com>
> ---
> kernel/trace/ftrace.c | 7 +++++--
> 1 file changed, 5 insertions(+), 2 deletions(-)
>
> diff --git a/kernel/trace/ftrace.c b/kernel/trace/ftrace.c
> index a12aff849c04..7e2488da69ac 100644
> --- a/kernel/trace/ftrace.c
> +++ b/kernel/trace/ftrace.c
> @@ -4221,10 +4221,13 @@ void free_ftrace_func_mapper(struct ftrace_func_mapper *mapper,
> struct ftrace_func_entry *entry;
> struct ftrace_func_map *map;
> struct hlist_head *hhd;
> - int size = 1 << mapper->hash.size_bits;
> - int i;
> + int size, i;
> +
> + if (!mapper)
> + return;
>
> if (free_func && mapper->hash.count) {
> + size = 1 << mapper->hash.size_bits;
> for (i = 0; i < size; i++) {
> hhd = &mapper->hash.buckets[i];
> hlist_for_each_entry(entry, hhd, hlist) {
^ permalink raw reply [flat|nested] 2+ messages in thread
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2019-06-06 3:17 [PATCH] ftrace: fix NULL pointer dereference in free_ftrace_func_mapper() Wei Li
2019-06-14 21:40 ` Steven Rostedt
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