On 17/09/2021 03:59, Marek Vasut wrote:
The return type of ktime_divns() is s64. The timeout_to_jiffies() currently
assigns the result of this ktime_divns() to unsigned long, which on 32 bit
systems may overflow. Furthermore, the result of this function is sometimes
also passed to functions which expect signed long, dma_fence_wait_timeout()
is one such example.
Fix this by adjusting the type of remaining_jiffies to s64, so we do not
suffer overflow there, and return a value limited to range of 0..INT_MAX,
which is safe for all usecases of this timeout.
The above overflow can be triggered if userspace passes in too large timeout
value, larger than INT_MAX / HZ seconds. The kernel detects it and complains
about "schedule_timeout: wrong timeout value %lx" and generates a warning
backtrace.
Note that this fixes commit 6cedb8b377bb ("drm/msm: avoid using 'timespec'"),
because the previously used timespec_to_jiffies() function returned unsigned
long instead of s64:
static inline unsigned long timespec_to_jiffies(const struct timespec *value)
Fixes: 6cedb8b377bb ("drm/msm: avoid using 'timespec'")
Signed-off-by: Marek Vasut <marex@xxxxxxx>
Cc: Arnd Bergmann <arnd@xxxxxxxx>
Cc: Jordan Crouse <jcrouse@xxxxxxxxxxxxxx>
Cc: Rob Clark <robdclark@xxxxxxxxxxxx>
Cc: stable@xxxxxxxxxxxxxxx # 5.6+
Reviewed-by: Dmitry Baryshkov <dmitry.baryshkov@xxxxxxxxxx>
---
NOTE: This is related to Mesa MR
https://gitlab.freedesktop.org/mesa/mesa/-/merge_requests/12886
---
drivers/gpu/drm/msm/msm_drv.h | 4 ++--
1 file changed, 2 insertions(+), 2 deletions(-)
diff --git a/drivers/gpu/drm/msm/msm_drv.h b/drivers/gpu/drm/msm/msm_drv.h
index 0b2686b060c73..d96b254b8aa46 100644
--- a/drivers/gpu/drm/msm/msm_drv.h
+++ b/drivers/gpu/drm/msm/msm_drv.h
@@ -543,7 +543,7 @@ static inline int align_pitch(int width, int bpp)
static inline unsigned long timeout_to_jiffies(const ktime_t *timeout)
{
ktime_t now = ktime_get();
- unsigned long remaining_jiffies;
+ s64 remaining_jiffies;
if (ktime_compare(*timeout, now) < 0) {
remaining_jiffies = 0;
@@ -552,7 +552,7 @@ static inline unsigned long timeout_to_jiffies(const ktime_t *timeout)
remaining_jiffies = ktime_divns(rem, NSEC_PER_SEC / HZ);
}
- return remaining_jiffies;
+ return clamp(remaining_jiffies, 0LL, (s64)INT_MAX);
}
#endif /* __MSM_DRV_H__ */
--
With best wishes
Dmitry
