[PATCH] remoteproc: qcom: Don't memcpy_toio more than is provided

Stephen Boyd
2021-11-17T06:54:59Z

If the string passed into qcom_pil_info_store() isn't as long as
PIL_RELOC_NAME_LEN we'll try to copy the string assuming the length is
PIL_RELOC_NAME_LEN to the io space and go beyond the bounds of the
string. Let's only copy as many byes as the string is long, ignoring the
NUL terminator.

This fixes the following KASAN error:

BUG: KASAN: global-out-of-bounds in __memcpy_toio+0x124/0x140
Read of size 1 at addr ffffffd35086e386 by task rmtfs/2392

CPU: 2 PID: 2392 Comm: rmtfs Tainted: G W 5.16.0-rc1-lockdep+ #10
Hardware name: Google Lazor (rev3+) with KB Backlight (DT)
Call trace:
dump_backtrace+0x0/0x410
show_stack+0x24/0x30
dump_stack_lvl+0x7c/0xa0
print_address_description+0x78/0x2bc
kasan_report+0x160/0x1a0
__asan_report_load1_noabort+0x44/0x50
__memcpy_toio+0x124/0x140
qcom_pil_info_store+0x298/0x358 [qcom_pil_info]
q6v5_start+0xdf0/0x12e0 [qcom_q6v5_mss]
rproc_start+0x178/0x3a0
rproc_boot+0x5f0/0xb90
state_store+0x78/0x1bc
dev_attr_store+0x70/0x90
sysfs_kf_write+0xf4/0x118
kernfs_fop_write_iter+0x208/0x300
vfs_write+0x55c/0x804
ksys_pwrite64+0xc8/0x134
__arm64_compat_sys_aarch32_pwrite64+0xc4/0xdc
invoke_syscall+0x78/0x20c
el0_svc_common+0x11c/0x1f0
do_el0_svc_compat+0x50/0x60
el0_svc_compat+0x5c/0xec
el0t_32_sync_handler+0xc0/0xf0
el0t_32_sync+0x1a4/0x1a8

The buggy address belongs to the variable:
.str.59+0x6/0xffffffffffffec80 [qcom_q6v5_mss]

Memory state around the buggy address:
ffffffd35086e280: 00 00 00 00 02 f9 f9 f9 f9 f9 f9 f9 00 00 00 00
ffffffd35086e300: 00 02 f9 f9 f9 f9 f9 f9 00 00 00 06 f9 f9 f9 f9
>ffffffd35086e380: 06 f9 f9 f9 05 f9 f9 f9 00 00 00 00 00 06 f9 f9
^
ffffffd35086e400: f9 f9 f9 f9 01 f9 f9 f9 04 f9 f9 f9 00 00 01 f9
ffffffd35086e480: f9 f9 f9 f9 00 00 00 00 00 00 00 01 f9 f9 f9 f9

Fixes: 549b67da660d ("remoteproc: qcom: Introduce helper to store pil info in IMEM")
Signed-off-by: Stephen Boyd <swboyd@chromium.org>
---
drivers/remoteproc/qcom_pil_info.c | 2 +-
1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/drivers/remoteproc/qcom_pil_info.c b/drivers/remoteproc/qcom_pil_info.c
index 7c007dd7b200..aca21560e20b 100644
--- a/drivers/remoteproc/qcom_pil_info.c
+++ b/drivers/remoteproc/qcom_pil_info.c
@@ -104,7 +104,7 @@ int qcom_pil_info_store(const char *image, phys_addr_t base, size_t size)
return -ENOMEM;

found_unused:
- memcpy_toio(entry, image, PIL_RELOC_NAME_LEN);
+ memcpy_toio(entry, image, strnlen(image, PIL_RELOC_NAME_LEN));
found_existing:
/* Use two writel() as base is only aligned to 4 bytes on odd entries */
writel(base, entry + PIL_RELOC_NAME_LEN);

base-commit: fa55b7dcdc43c1aa1ba12bca9d2dd4318c2a0dbf
--