Forcing an int to be dereferenced at uint64_t for div64_u64_rem() runs
the risk of endian confusion and stack overflowing writes. Seen while
preparing to enable -Warray-bounds globally:
In file included from ../arch/x86/include/asm/processor.h:35,
from ../include/linux/sched.h:13,
from ../include/linux/ratelimit.h:6,
from ../include/linux/dev_printk.h:16,
from ../drivers/gpu/drm/amd/amdgpu/../ras/ras_mgr/ras_sys.h:29,
from ../drivers/gpu/drm/amd/amdgpu/../ras/rascore/ras.h:27,
from
../drivers/gpu/drm/amd/amdgpu/../ras/rascore/ras_core.c:24:
In function 'div64_u64_rem',
inlined from 'ras_core_convert_timestamp_to_time' at
../drivers/gpu/drm/amd/amdgpu/../ras/rascore/ras_core.c:72:9:
../include/linux/math64.h:56:20: error: array subscript 'u64 {aka long long
unsigned int}[0]' is partly outside array bounds of 'int[1]'
[-Werror=array-bounds=]
56 | *remainder = dividend % divisor;
| ~~~~~~~~~~~^~~~~~~~~~~~~~~~~~~~
../drivers/gpu/drm/amd/amdgpu/../ras/rascore/ras_core.c: In function
'ras_core_convert_timestamp_to_time':
../drivers/gpu/drm/amd/amdgpu/../ras/rascore/ras_core.c:70:19: note: object
'remaining_seconds' of size 4
70 | int days, remaining_seconds;
| ^~~~~~~~~~~~~~~~~
Use a 64-bit type for the remainder calculation, but leave
remaining_seconds as 32-bit to avoid 64-bit division later. The value of
remainder will always be less than seconds_per_day, so there's no
truncation risk.
Fixes: ace232eff50e ("drm/amdgpu: Add ras module files into amdgpu")
Signed-off-by: Kees Cook <[email protected]>
---
v2: use temp u64 to avoid 64-bit division later
v1: https://lore.kernel.org/lkml/[email protected]/
Cc: Alex Deucher <[email protected]>
Cc: "Christian König" <[email protected]>
Cc: David Airlie <[email protected]>
Cc: Simona Vetter <[email protected]>
Cc: YiPeng Chai <[email protected]>
Cc: Tao Zhou <[email protected]>
Cc: Hawking Zhang <[email protected]>
Cc: <[email protected]>
Cc: <[email protected]>
---
drivers/gpu/drm/amd/ras/rascore/ras_core.c | 6 ++++--
1 file changed, 4 insertions(+), 2 deletions(-)
diff --git a/drivers/gpu/drm/amd/ras/rascore/ras_core.c
b/drivers/gpu/drm/amd/ras/rascore/ras_core.c
index 01122b55c98a..02bbee64a5bd 100644
--- a/drivers/gpu/drm/amd/ras/rascore/ras_core.c
+++ b/drivers/gpu/drm/amd/ras/rascore/ras_core.c
@@ -62,14 +62,16 @@ int ras_core_convert_timestamp_to_time(struct
ras_core_context *ras_core,
uint64_t timestamp, struct ras_time *tm)
{
int days_in_month[] = {31, 28, 31, 30, 31, 30, 31, 31, 30, 31, 30, 31};
- uint64_t month = 0, day = 0, hour = 0, minute = 0, second = 0;
+ uint64_t month = 0, day = 0, hour = 0, minute = 0, second = 0,
remainder;
uint32_t year = 0;
int seconds_per_day = 24 * 60 * 60;
int seconds_per_hour = 60 * 60;
int seconds_per_minute = 60;
int days, remaining_seconds;
- days = div64_u64_rem(timestamp, seconds_per_day, (uint64_t
*)&remaining_seconds);
+ days = div64_u64_rem(timestamp, seconds_per_day, &remainder);
+ /* remainder will always be less than seconds_per_day. */
+ remaining_seconds = remainder;
/* utc_timestamp follows the Unix epoch */
year = 1970;
--
2.34.1
