From 51d8a7eca67784b155a07aeab4bfb9f63ebaaf9e Mon Sep 17 00:00:00 2001 From: Christian Brauner Date: Tue, 8 Oct 2019 15:01:59 +0200 Subject: [PATCH] binder: prevent UAF read in print_binder_transaction_log_entry() When a binder transaction is initiated on a binder device coming from a binderfs instance, a pointer to the name of the binder device is stashed in the binder_transaction_log_entry's context_name member. Later on it is used to print the name in print_binder_transaction_log_entry(). By the time print_binder_transaction_log_entry() accesses context_name binderfs_evict_inode() might have already freed the associated memory thereby causing a UAF. Do the simple thing and prevent this by copying the name of the binder device instead of stashing a pointer to it. Reported-by: Jann Horn Fixes: 03e2e07e3814 ("binder: Make transaction_log available in binderfs") Link: https://lore.kernel.org/r/CAG48ez14Q0-F8LqsvcNbyR2o6gPW8SHXsm4u5jmD9MpsteM2Tw@mail.gmail.com Signed-off-by: Christian Brauner Reviewed-by: Joel Fernandes (Google) Acked-by: Todd Kjos Reviewed-by: Hridya Valsaraju Link: https://lore.kernel.org/r/20191008130159.10161-1-christian.brauner@ubuntu.com Signed-off-by: Greg Kroah-Hartman --- drivers/android/binder.c | 4 +++- drivers/android/binder_internal.h | 2 +- 2 files changed, 4 insertions(+), 2 deletions(-) diff --git a/drivers/android/binder.c b/drivers/android/binder.c index c0a491277aca..5b9ac2122e89 100644 --- a/drivers/android/binder.c +++ b/drivers/android/binder.c @@ -57,6 +57,7 @@ #include #include #include +#include #include #include #include @@ -66,6 +67,7 @@ #include #include +#include #include @@ -2876,7 +2878,7 @@ static void binder_transaction(struct binder_proc *proc, e->target_handle = tr->target.handle; e->data_size = tr->data_size; e->offsets_size = tr->offsets_size; - e->context_name = proc->context->name; + strscpy(e->context_name, proc->context->name, BINDERFS_MAX_NAME); if (reply) { binder_inner_proc_lock(proc); diff --git a/drivers/android/binder_internal.h b/drivers/android/binder_internal.h index bd47f7f72075..ae991097d14d 100644 --- a/drivers/android/binder_internal.h +++ b/drivers/android/binder_internal.h @@ -130,7 +130,7 @@ struct binder_transaction_log_entry { int return_error_line; uint32_t return_error; uint32_t return_error_param; - const char *context_name; + char context_name[BINDERFS_MAX_NAME + 1]; }; struct binder_transaction_log {