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Code Issues Releases Wiki Activity

binder_alloc: add missing mmap_lock calls when using the VMA 

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.

Link: https://lkml.kernel.org/r/20220810160209.1630707-1-Liam.Howlett@oracle.com
Fixes: a43cfc87ca (android: binder: stop saving a pointer to the VMA)
Signed-off-by: Liam R. Howlett <Liam.Howlett@oracle.com>
Reported-by: Ondrej Mosnacek <omosnace@redhat.com>
Reported-by: <syzbot+a7b60a176ec13cafb793@syzkaller.appspotmail.com>
Acked-by: Carlos Llamas <cmllamas@google.com>
Tested-by: Ondrej Mosnacek <omosnace@redhat.com>
Cc: Minchan Kim <minchan@kernel.org>
Cc: Christian Brauner (Microsoft) <brauner@kernel.org>
Cc: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Cc: Hridya Valsaraju <hridya@google.com>
Cc: Joel Fernandes <joel@joelfernandes.org>
Cc: Martijn Coenen <maco@android.com>
Cc: Suren Baghdasaryan <surenb@google.com>
Cc: Todd Kjos <tkjos@android.com>
Cc: Matthew Wilcox (Oracle) <willy@infradead.org>
Cc: "Arve Hjønnevåg" <arve@android.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
This commit is contained in:
Liam Howlett 2022-08-10 16:02:25 +00:00 committed by Andrew Morton
parent fcab34b433
commit 44e602b4e5
1 changed files with 21 additions and 10 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

31
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 *));
@ -929,17 +932,25 @@ 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) {
for (i = 0; i < alloc->buffer_size / PAGE_SIZE; i++) {
page = &alloc->pages[i];
if (!page->page_ptr)
free++;
else if (list_empty(&page->lru))
active++;
else
lru++;
}
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)
free++;
else if (list_empty(&page->lru))
active++;
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);