signals, ptrace, sched: Fix a misaligned load inside ptrace_attach()

palmer-dabbelt · Ingo Molnar · commit e7cc41731153 · 2015-05-08T12:06:57.000+02:00
The misaligned load exception arises when running ptrace_attach() on the RISC-V (which hasn't been upstreamed yet). The problem is that wait_on_bit() takes a void* but then proceeds to call test_bit(), which takes a long*. This allows an int-aligned pointer to be passed to test_bit(), which promptly fails. This will manifest on any other asm-generic port where unaligned loads trap, where sizeof(long) > sizeof(int), and where task_struct.jobctl ends up not being long-aligned. This patch changes task_struct.jobctl to be a long, which ensures it has the correct alignment. Signed-off-by: Palmer Dabbelt <palmer@dabbelt.com> Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org> Reviewed-by: Chris Metcalf <cmetcalf@ezchip.com> Cc: Andrew Morton <akpm@linux-foundation.org> Cc: Borislav Petkov <bp@alien8.de> Cc: H. Peter Anvin <hpa@zytor.com> Cc: Linus Torvalds <torvalds@linux-foundation.org> Cc: Thomas Gleixner <tglx@linutronix.de> Cc: bobby.prani@gmail.com Cc: oleg@redhat.com Cc: paulmck@linux.vnet.ibm.com Cc: richard@nod.at Cc: vdavydov@parallels.com Link: http://lkml.kernel.org/r/1430453997-32459-2-git-send-email-palmer@dabbelt.com Signed-off-by: Ingo Molnar <mingo@kernel.org>
diff --git a/include/linux/sched.h b/include/linux/sched.h
@@ -1374,7 +1374,7 @@ struct task_struct {
 	int exit_state;
 	int exit_code, exit_signal;
 	int pdeath_signal;  /*  The signal sent when the parent dies  */
-	unsigned int jobctl;	/* JOBCTL_*, siglock protected */
+	unsigned long jobctl;	/* JOBCTL_*, siglock protected */
 
 	/* Used for emulating ABI behavior of previous Linux versions */
 	unsigned int personality;
