diff options
| author | Todd Kjos <tkjos@android.com> | 2019-02-14 15:22:57 -0800 |
|---|---|---|
| committer | Greg Kroah-Hartman <gregkh@linuxfoundation.org> | 2019-05-02 09:40:31 +0200 |
| commit | 33c6b9ca70a8b066a613e2a3d0331ae8f82aa31a (patch) | |
| tree | 607c223e97e794456be97b65dd278d62cd558852 /drivers/android | |
| parent | 44579653c9ab9bb1be04888f285ba4c20c924217 (diff) | |
binder: fix handling of misaligned binder object
commit 26528be6720bb40bc8844e97ee73a37e530e9c5e upstream.
Fixes crash found by syzbot:
kernel BUG at drivers/android/binder_alloc.c:LINE! (2)
Reported-and-tested-by: syzbot+55de1eb4975dec156d8f@syzkaller.appspotmail.com
Signed-off-by: Todd Kjos <tkjos@google.com>
Reviewed-by: Joel Fernandes (Google) <joel@joelfernandes.org>
Cc: stable <stable@vger.kernel.org> # 5.0, 4.19, 4.14
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Diffstat (limited to 'drivers/android')
| -rw-r--r-- | drivers/android/binder_alloc.c | 18 |
1 files changed, 8 insertions, 10 deletions
diff --git a/drivers/android/binder_alloc.c b/drivers/android/binder_alloc.c index b9281f2725a6..e0b0399ff7ec 100644 --- a/drivers/android/binder_alloc.c +++ b/drivers/android/binder_alloc.c @@ -945,14 +945,13 @@ enum lru_status binder_alloc_free_page(struct list_head *item, index = page - alloc->pages; page_addr = (uintptr_t)alloc->buffer + index * PAGE_SIZE; + + mm = alloc->vma_vm_mm; + if (!mmget_not_zero(mm)) + goto err_mmget; + if (!down_write_trylock(&mm->mmap_sem)) + goto err_down_write_mmap_sem_failed; vma = binder_alloc_get_vma(alloc); - if (vma) { - if (!mmget_not_zero(alloc->vma_vm_mm)) - goto err_mmget; - mm = alloc->vma_vm_mm; - if (!down_write_trylock(&mm->mmap_sem)) - goto err_down_write_mmap_sem_failed; - } list_lru_isolate(lru, item); spin_unlock(lock); @@ -965,10 +964,9 @@ enum lru_status binder_alloc_free_page(struct list_head *item, PAGE_SIZE); trace_binder_unmap_user_end(alloc, index); - - up_write(&mm->mmap_sem); - mmput(mm); } + up_write(&mm->mmap_sem); + mmput(mm); trace_binder_unmap_kernel_start(alloc, index); |