diff options
| author | haibinzhang (张海斌) <haibinzhang@tencent.com> | 2022-07-02 05:43:19 +0000 |
|---|---|---|
| committer | Todd Kjos <tkjos@google.com> | 2022-08-17 12:51:00 -0700 |
| commit | bb1540be070e05779e61e7364fea38f44cb6f716 (patch) | |
| tree | c37892608acda5f6d3f7497cdae180bc5cb3a0e7 | |
| parent | 60f3188cf9c838cf6c220be01895a3a78a0023f8 (diff) | |
| download | common-android14-trusty-5.15.tar.gz | |
FROMGIT: arm64: fix oops in concurrently setting insn_emulation sysctlsandroid14-trusty-5.15
emulation_proc_handler() changes table->data for proc_dointvec_minmax
and can generate the following Oops if called concurrently with itself:
| Unable to handle kernel NULL pointer dereference at virtual address 0000000000000010
| Internal error: Oops: 96000006 [#1] SMP
| Call trace:
| update_insn_emulation_mode+0xc0/0x148
| emulation_proc_handler+0x64/0xb8
| proc_sys_call_handler+0x9c/0xf8
| proc_sys_write+0x18/0x20
| __vfs_write+0x20/0x48
| vfs_write+0xe4/0x1d0
| ksys_write+0x70/0xf8
| __arm64_sys_write+0x20/0x28
| el0_svc_common.constprop.0+0x7c/0x1c0
| el0_svc_handler+0x2c/0xa0
| el0_svc+0x8/0x200
To fix this issue, keep the table->data as &insn->current_mode and
use container_of() to retrieve the insn pointer. Another mutex is
used to protect against the current_mode update but not for retrieving
insn_emulation as table->data is no longer changing.
Bug: 237540956
Co-developed-by: hewenliang <hewenliang4@huawei.com>
Signed-off-by: hewenliang <hewenliang4@huawei.com>
Signed-off-by: Haibin Zhang <haibinzhang@tencent.com>
Reviewed-by: Catalin Marinas <catalin.marinas@arm.com>
Link: https://lore.kernel.org/r/20220128090324.2727688-1-hewenliang4@huawei.com
Link: https://lore.kernel.org/r/9A004C03-250B-46C5-BF39-782D7551B00E@tencent.com
Signed-off-by: Will Deacon <will@kernel.org>
[Lee: Added Fixes: tag]
(cherry picked from commit af483947d472eccb79e42059276c4deed76f99a6
git://git.kernel.org/pub/scm/linux/kernel/git/arm64/linux.git for-next/core)
Fixes: 587064b610c7 ("arm64: Add framework for legacy instruction emulation")
Signed-off-by: Lee Jones <joneslee@google.com>
Change-Id: If9b96bb79c79903f9d8292e719b06fdef57ef1c5
| -rw-r--r-- | arch/arm64/kernel/armv8_deprecated.c | 9 |
1 files changed, 5 insertions, 4 deletions
diff --git a/arch/arm64/kernel/armv8_deprecated.c b/arch/arm64/kernel/armv8_deprecated.c index 0e86e8b9cedd..c5da9d1e954a 100644 --- a/arch/arm64/kernel/armv8_deprecated.c +++ b/arch/arm64/kernel/armv8_deprecated.c @@ -59,6 +59,7 @@ struct insn_emulation { static LIST_HEAD(insn_emulation); static int nr_insn_emulated __initdata; static DEFINE_RAW_SPINLOCK(insn_emulation_lock); +static DEFINE_MUTEX(insn_emulation_mutex); static void register_emulation_hooks(struct insn_emulation_ops *ops) { @@ -207,10 +208,10 @@ static int emulation_proc_handler(struct ctl_table *table, int write, loff_t *ppos) { int ret = 0; - struct insn_emulation *insn = (struct insn_emulation *) table->data; + struct insn_emulation *insn = container_of(table->data, struct insn_emulation, current_mode); enum insn_emulation_mode prev_mode = insn->current_mode; - table->data = &insn->current_mode; + mutex_lock(&insn_emulation_mutex); ret = proc_dointvec_minmax(table, write, buffer, lenp, ppos); if (ret || !write || prev_mode == insn->current_mode) @@ -223,7 +224,7 @@ static int emulation_proc_handler(struct ctl_table *table, int write, update_insn_emulation_mode(insn, INSN_UNDEF); } ret: - table->data = insn; + mutex_unlock(&insn_emulation_mutex); return ret; } @@ -247,7 +248,7 @@ static void __init register_insn_emulation_sysctl(void) sysctl->maxlen = sizeof(int); sysctl->procname = insn->ops->name; - sysctl->data = insn; + sysctl->data = &insn->current_mode; sysctl->extra1 = &insn->min; sysctl->extra2 = &insn->max; sysctl->proc_handler = emulation_proc_handler; |