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Code Issues Releases Wiki Activity

binder: fix handling of misaligned binder object

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commit 26528be672 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>
This commit is contained in:
Todd Kjos 2019-02-14 15:22:57 -08:00 committed by Greg Kroah-Hartman
parent 8c37f7c23c
commit 6bf7d3c5c0
1 changed files with 8 additions and 10 deletions
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18
drivers/android/binder_alloc.c
View file

@ -958,14 +958,13 @@ 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);
@ -978,10 +977,9 @@ 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);