| lists.openwall.net | lists / announce owl-users owl-dev john-users john-dev passwdqc-users yescrypt popa3d-users / oss-security kernel-hardening musl sabotage tlsify passwords / crypt-dev xvendor / Bugtraq Full-Disclosure linux-kernel linux-netdev linux-ext4 linux-hardening linux-cve-announce PHC | |
|
Open Source and information security mailing list archives
| ||
|
Message-ID: <20190614174004.1e2efef4@gandalf.local.home>
Date: Fri, 14 Jun 2019 17:40:04 -0400
From: Steven Rostedt <rostedt@...dmis.org>
To: Wei Li <liwei391@...wei.com>
Cc: <mingo@...hat.com>, <huawei.libin@...wei.com>,
<linux-kernel@...r.kernel.org>
Subject: Re: [PATCH] ftrace: fix NULL pointer dereference in
free_ftrace_func_mapper()
On Thu, 6 Jun 2019 11:17:54 +0800
Wei Li <liwei391@...wei.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@...wei.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) {
Powered by blists - more mailing lists