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authorAlessandro Astone <ales.astone@gmail.com>2022-04-15 14:00:14 +0200
committerGreg Kroah-Hartman <gregkh@linuxfoundation.org>2022-04-22 17:22:51 +0200
commitef38de9217a04c9077629a24652689d8fdb4c6c6 (patch)
tree238222878c25d6e32441102babbc9f60922e7842
parent2d1746e3fda0c3612143d7c06f8e1d1830c13e23 (diff)
downloadlinux-ef38de9217a04c9077629a24652689d8fdb4c6c6.tar.bz2
binder: Gracefully handle BINDER_TYPE_FDA objects with num_fds=0
Some android userspace is sending BINDER_TYPE_FDA objects with num_fds=0. Like the previous patch, this is reproducible when playing a video. Before commit 09184ae9b575 BINDER_TYPE_FDA objects with num_fds=0 were 'correctly handled', as in no fixup was performed. After commit 09184ae9b575 we aggregate fixup and skip regions in binder_ptr_fixup structs and distinguish between the two by using the skip_size field: if it's 0, then it's a fixup, otherwise skip. When processing BINDER_TYPE_FDA objects with num_fds=0 we add a skip region of skip_size=0, and this causes issues because now binder_do_deferred_txn_copies will think this was a fixup region. To address that, return early from binder_translate_fd_array to avoid adding an empty skip region. Fixes: 09184ae9b575 ("binder: defer copies of pre-patched txn data") Acked-by: Todd Kjos <tkjos@google.com> Cc: stable <stable@kernel.org> Signed-off-by: Alessandro Astone <ales.astone@gmail.com> Link: https://lore.kernel.org/r/20220415120015.52684-1-ales.astone@gmail.com Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
-rw-r--r--drivers/android/binder.c3
1 files changed, 3 insertions, 0 deletions
diff --git a/drivers/android/binder.c b/drivers/android/binder.c
index 31176edb1069..f3b639e89dd8 100644
--- a/drivers/android/binder.c
+++ b/drivers/android/binder.c
@@ -2491,6 +2491,9 @@ static int binder_translate_fd_array(struct list_head *pf_head,
struct binder_proc *proc = thread->proc;
int ret;
+ if (fda->num_fds == 0)
+ return 0;
+
fd_buf_size = sizeof(u32) * fda->num_fds;
if (fda->num_fds >= SIZE_MAX / sizeof(u32)) {
binder_user_error("%d:%d got transaction with invalid number of fds (%lld)\n",