The patch titled
Subject: binder_alloc: add missing mmap_lock calls when using the VMA
has been added to the -mm mm-hotfixes-unstable branch. Its filename is
binder_alloc-add-missing-mmap_lock-calls-when-using-the-vma.patch
This patch will shortly appear at
https://git.kernel.org/pub/scm/linux/kernel/git/akpm/25-new.git/tree/patches/binder_alloc-add-missing-mmap_lock-calls-when-using-the-vma.patch
This patch will later appear in the mm-hotfixes-unstable branch at
git://git.kernel.org/pub/scm/linux/kernel/git/akpm/mm
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------------------------------------------------------
From: Liam Howlett <liam.howlett@xxxxxxxxxx>
Subject: binder_alloc: add missing mmap_lock calls when using the VMA
Date: Tue, 9 Aug 2022 16:06:31 +0000
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/20220809160618.1052539-1-Liam.Howlett@xxxxxxxxxx
Fixes: a43cfc87caaf ("android: binder: stop saving a pointer to the VMA")
Signed-off-by: Liam R. Howlett <Liam.Howlett@xxxxxxxxxx>
Reported-by: Ondrej Mosnacek <omosnace@xxxxxxxxxx>
Reported-by: syzbot+a7b60a176ec13cafb793@xxxxxxxxxxxxxxxxxxxxxxxxx
Cc: Minchan Kim <minchan@xxxxxxxxxx>
Cc: Christian Brauner (Microsoft) <brauner@xxxxxxxxxx>
Cc: Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx>
Cc: Hridya Valsaraju <hridya@xxxxxxxxxx>
Cc: Joel Fernandes <joel@xxxxxxxxxxxxxxxxx>
Cc: Martijn Coenen <maco@xxxxxxxxxxx>
Cc: Suren Baghdasaryan <surenb@xxxxxxxxxx>
Cc: Todd Kjos <tkjos@xxxxxxxxxxx>
Cc: Matthew Wilcox (Oracle) <willy@xxxxxxxxxxxxx>
Cc: "Arve Hjønnevåg" <arve@xxxxxxxxxxx>
Cc: Carlos Llamas <cmllamas@xxxxxxxxxx>
Signed-off-by: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx>
---
drivers/android/binder_alloc.c | 29 +++++++++++++++++++----------
1 file changed, 19 insertions(+), 10 deletions(-)
--- a/drivers/android/binder_alloc.c~binder_alloc-add-missing-mmap_lock-calls-when-using-the-vma
+++ a/drivers/android/binder_alloc.c
@@ -402,12 +402,15 @@ static struct binder_buffer *binder_allo
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 +932,23 @@ void binder_alloc_print_pages(struct seq
* 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)
+ goto uninitialized;
+
+ 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:
+ mmap_read_unlock(alloc->vma_vm_mm);
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);
_
Patches currently in -mm which might be from liam.howlett@xxxxxxxxxx are
binder_alloc-add-missing-mmap_lock-calls-when-using-the-vma.patch
