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@denx.de Cc: Arnd Bergmann arnd@arndb.de Cc: Jordan Crouse jcrouse@codeaurora.org Cc: Rob Clark robdclark@chromium.org Cc: stable@vger.kernel.org # 5.6+ --- 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__ */
On Fri, Sep 17, 2021 at 2:59 AM Marek Vasut marex@denx.de 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@denx.de Cc: Arnd Bergmann arnd@arndb.de Cc: Jordan Crouse jcrouse@codeaurora.org Cc: Rob Clark robdclark@chromium.org Cc: stable@vger.kernel.org # 5.6+
Acked-by: Arnd Bergmann arnd@arndb.de
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@denx.de Cc: Arnd Bergmann arnd@arndb.de Cc: Jordan Crouse jcrouse@codeaurora.org Cc: Rob Clark robdclark@chromium.org Cc: stable@vger.kernel.org # 5.6+
Reviewed-by: Dmitry Baryshkov dmitry.baryshkov@linaro.org
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__ */
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Arnd Bergmann -
Dmitry Baryshkov -
Marek Vasut