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binder_alloc: Add missing mmap_lock calls when using the VMA

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Take the mmap_read_lock() when using the VMA in
binder_alloc_print_pages() and when checking for a VMA in
binder_alloc_new_buf_locked().

It is worth noting binder_alloc_new_buf_locked() drops the VMA read lock
after it verifies a VMA exists, but may be taken again deeper in the
call stack, if necessary.

Fixes: a43cfc87ca (android: binder: stop saving a pointer to the VMA)
Cc: stable <stable@kernel.org>
Reported-by: Ondrej Mosnacek <omosnace@redhat.com>
Reported-by: syzbot+a7b60a176ec13cafb793@syzkaller.appspotmail.com
Tested-by: Ondrej Mosnacek <omosnace@redhat.com>
Acked-by: Carlos Llamas <cmllamas@google.com>
Signed-off-by: Liam R. Howlett <Liam.Howlett@oracle.com>
Link: https://lore.kernel.org/r/20220810160209.1630707-1-Liam.Howlett@oracle.com
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
This commit is contained in:
Liam Howlett 2022-08-10 16:02:25 +00:00 committed by Greg Kroah-Hartman
parent a0e44c64b6
commit d6f35446d0
1 changed files with 21 additions and 10 deletions
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15
drivers/android/binder_alloc.c
View File

@ -402,12 +402,15 @@ static struct binder_buffer *binder_alloc_new_buf_locked(
size_t size, data_offsets_size;
int ret;
mmap_read_lock(alloc->vma_vm_mm);
if (!binder_alloc_get_vma(alloc)) {
mmap_read_unlock(alloc->vma_vm_mm);
binder_alloc_debug(BINDER_DEBUG_USER_ERROR,
"%d: binder_alloc_buf, no vma\n",
alloc->pid);
return ERR_PTR(-ESRCH);
}
mmap_read_unlock(alloc->vma_vm_mm);
data_offsets_size = ALIGN(data_size, sizeof(void *)) +
ALIGN(offsets_size, sizeof(void *));
@ -929,7 +932,14 @@ void binder_alloc_print_pages(struct seq_file *m,
* Make sure the binder_alloc is fully initialized, otherwise we might
* read inconsistent state.
*/
if (binder_alloc_get_vma(alloc) != NULL) {
mmap_read_lock(alloc->vma_vm_mm);
if (binder_alloc_get_vma(alloc) == NULL) {
mmap_read_unlock(alloc->vma_vm_mm);
goto uninitialized;
}
mmap_read_unlock(alloc->vma_vm_mm);
for (i = 0; i < alloc->buffer_size / PAGE_SIZE; i++) {
page = &alloc->pages[i];
if (!page->page_ptr)
@ -939,7 +949,8 @@ void binder_alloc_print_pages(struct seq_file *m,
else
lru++;
}
}
uninitialized:
mutex_unlock(&alloc->mutex);
seq_printf(m, " pages: %d:%d:%d\n", active, lru, free);
seq_printf(m, " pages high watermark: %zu\n", alloc->pages_high);