| Message ID | 20210917005913.157379-1-marex@denx.de (mailing list archive) |
|---|---|
| State | New, archived |
| Headers | show |
| Series | drm/msm: Avoid potential overflow in timeout_to_jiffies() | expand |
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__ */ >
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__ */
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(-)