Commit 51d8a7ec authored by Christian Brauner's avatar Christian Brauner Committed by Greg Kroah-Hartman

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: default avatarJann Horn <jannh@google.com>
Fixes: 03e2e07e ("binder: Make transaction_log available in binderfs")
Link: https://lore.kernel.org/r/CAG48ez14Q0-F8LqsvcNbyR2o6gPW8SHXsm4u5jmD9MpsteM2Tw@mail.gmail.comSigned-off-by: default avatarChristian Brauner <christian.brauner@ubuntu.com>
Reviewed-by: default avatarJoel Fernandes (Google) <joel@joelfernandes.org>
Acked-by: default avatarTodd Kjos <tkjos@google.com>
Reviewed-by: default avatarHridya Valsaraju <hridya@google.com>
Link: https://lore.kernel.org/r/20191008130159.10161-1-christian.brauner@ubuntu.comSigned-off-by: default avatarGreg Kroah-Hartman <gregkh@linuxfoundation.org>
parent fc739a05
...@@ -57,6 +57,7 @@ ...@@ -57,6 +57,7 @@
#include <linux/sched/signal.h> #include <linux/sched/signal.h>
#include <linux/sched/mm.h> #include <linux/sched/mm.h>
#include <linux/seq_file.h> #include <linux/seq_file.h>
#include <linux/string.h>
#include <linux/uaccess.h> #include <linux/uaccess.h>
#include <linux/pid_namespace.h> #include <linux/pid_namespace.h>
#include <linux/security.h> #include <linux/security.h>
...@@ -66,6 +67,7 @@ ...@@ -66,6 +67,7 @@
#include <linux/task_work.h> #include <linux/task_work.h>
#include <uapi/linux/android/binder.h> #include <uapi/linux/android/binder.h>
#include <uapi/linux/android/binderfs.h>
#include <asm/cacheflush.h> #include <asm/cacheflush.h>
...@@ -2876,7 +2878,7 @@ static void binder_transaction(struct binder_proc *proc, ...@@ -2876,7 +2878,7 @@ static void binder_transaction(struct binder_proc *proc,
e->target_handle = tr->target.handle; e->target_handle = tr->target.handle;
e->data_size = tr->data_size; e->data_size = tr->data_size;
e->offsets_size = tr->offsets_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) { if (reply) {
binder_inner_proc_lock(proc); binder_inner_proc_lock(proc);
......
...@@ -130,7 +130,7 @@ struct binder_transaction_log_entry { ...@@ -130,7 +130,7 @@ struct binder_transaction_log_entry {
int return_error_line; int return_error_line;
uint32_t return_error; uint32_t return_error;
uint32_t return_error_param; uint32_t return_error_param;
const char *context_name; char context_name[BINDERFS_MAX_NAME + 1];
}; };
struct binder_transaction_log { struct binder_transaction_log {
......
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