diff options
| author | Christopher Lais <chris+android@zenthought.org> | 2010-05-01 15:51:48 -0500 |
|---|---|---|
| committer | Greg Kroah-Hartman <gregkh@suse.de> | 2011-11-30 20:51:37 +0900 |
| commit | 58526090ece3582516e62779739a7d665a74708c (patch) | |
| tree | 3bef2705ebe51c3d0e4f0b8dfee3379b9074a57c /drivers/staging/android | |
| parent | 4755b72e261478b48337e0e54c8448cbea32c5c8 (diff) | |
staging: binder: Fix memory corruption via page aliasing
binder_deferred_release was not unmapping the page from the buffer
before freeing it, causing memory corruption. This only happened
when page(s) had not been freed by binder_update_page_range, which
properly unmaps the pages.
This only happens on architectures with VIPT aliasing.
To reproduce, create a program which opens, mmaps, munmaps, then closes
the binder very quickly. This should leave a page allocated when the
binder is released. When binder_deferrred_release is called on the
close, the page will remain mapped to the address in the linear
proc->buffer. Later, we may map the same physical page to a different
virtual address that has different coloring, and this may cause
aliasing to occur.
PAGE_POISONING will greatly increase your chances of noticing any
problems.
Signed-off-by: Christopher Lais <chris+android@zenthought.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>
Diffstat (limited to 'drivers/staging/android')
| -rw-r--r-- | drivers/staging/android/binder.c | 5 |
1 files changed, 4 insertions, 1 deletions
diff --git a/drivers/staging/android/binder.c b/drivers/staging/android/binder.c index 6d6fe7bdebd3..7491801a661c 100644 --- a/drivers/staging/android/binder.c +++ b/drivers/staging/android/binder.c @@ -3036,11 +3036,14 @@ static void binder_deferred_release(struct binder_proc *proc) int i; for (i = 0; i < proc->buffer_size / PAGE_SIZE; i++) { if (proc->pages[i]) { + void *page_addr = proc->buffer + i * PAGE_SIZE; binder_debug(BINDER_DEBUG_BUFFER_ALLOC, "binder_release: %d: " "page %d at %p not freed\n", proc->pid, i, - proc->buffer + i * PAGE_SIZE); + page_addr); + unmap_kernel_range((unsigned long)page_addr, + PAGE_SIZE); __free_page(proc->pages[i]); page_count++; } |