From 171316a68d9a8e0d9e28b7cf4c15afc4c6244a4e Mon Sep 17 00:00:00 2001 From: Marek Vasut Date: Fri, 17 Sep 2021 02:59:13 +0200 Subject: [PATCH] drm/msm: Avoid potential overflow in timeout_to_jiffies() 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 Cc: Arnd Bergmann Cc: Jordan Crouse Cc: Rob Clark Cc: stable@vger.kernel.org # 5.6+ Acked-by: Arnd Bergmann Reviewed-by: Dmitry Baryshkov Link: https://lore.kernel.org/r/20210917005913.157379-1-marex@denx.de Signed-off-by: Rob Clark --- 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 e992421..c552f0c 100644 --- a/drivers/gpu/drm/msm/msm_drv.h +++ b/drivers/gpu/drm/msm/msm_drv.h @@ -504,7 +504,7 @@ 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; @@ -513,7 +513,7 @@ 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__ */ -- 2.7.4