On Mon, Mar 19, 2018 at 03:16:51PM -0700, Joel Fernandes (Google) wrote: > On Tue, Feb 27, 2018 at 10:59 PM, Yisheng Xie <xieyisheng1@xxxxxxxxxx> wrote: > > ashmem_mutex may create a chain of dependencies like: > > > > CPU0 CPU1 > > mmap syscall ioctl syscall > > -> mmap_sem (acquired) -> ashmem_ioctl > > -> ashmem_mmap -> ashmem_mutex (acquired) > > -> ashmem_mutex (try to acquire) -> copy_from_user > > -> mmap_sem (try to acquire) > > > > There is a lock odering problem between mmap_sem and ashmem_mutex causing > > a lockdep splat[1] during a syzcaller test. This patch fixes the problem > > by move copy_from_user out of ashmem_mutex. > > > > [1] https://www.spinics.net/lists/kernel/msg2733200.html > > > > Fixes: ce8a3a9e76d0 (staging: android: ashmem: Fix a race condition in pin ioctls) > > Reported-by: syzbot+d7a918a7a8e1c952bc36@xxxxxxxxxxxxxxxxxxxxxxxxx > > Signed-off-by: Yisheng Xie <xieyisheng1@xxxxxxxxxx> > > Greg, > Could you take this patch for the stable trees? I do see it in staging > already. I couldn't find it in stable so wanted to bring it to your > attention. If you already aware of it, please ignore my note. Ah, I didn't realize this needed to be added to the stable trees, I'll queue it up after this current round of releases happen in a few days. thanks, greg k-h _______________________________________________ devel mailing list devel@xxxxxxxxxxxxxxxxxxxxxx http://driverdev.linuxdriverproject.org/mailman/listinfo/driverdev-devel
