Merge tag 'random_for_linus_stable' of git://git.kernel.org/pub/scm/linux/kernel/git/tytso/random

5a4829b5 · Linus Torvalds <[email protected]> · 2017-06-02 16:19:47 -07:00

Pull /dev/random bug fix from Ted Ts'o:
 "Fix a race on architectures with prioritized interrupts (such as m68k)
  which can causes crashes in drivers/char/random.c:get_reg()"

* tag 'random_for_linus_stable' of git://git.kernel.org/pub/scm/linux/kernel/git/tytso/random:
  fix race in drivers/char/random.c:get_reg()

Commit: 5a4829b564d2f69574dc55bba2ada3ee72022187
Parents: f2197649 · 9dfa7bba

Merge commit. Changes below are compared with the first parent: f2197649.

Changes

1 files changed · +5 −1

File	Status	Add	Del	Content
drivers/char/random.c	modified	+5	−1	View file

drivers/char/random.c

View file

diff --git a/drivers/char/random.c b/drivers/char/random.c
index 0ab0249..a561f0c 100644
--- a/drivers/char/random.c
+++ b/drivers/char/random.c
@@ -1097,12 +1097,16 @@ static void add_interrupt_bench(cycles_t start)
 static __u32 get_reg(struct fast_pool *f, struct pt_regs *regs)
 {
 	__u32 *ptr = (__u32 *) regs;
+	unsigned long flags;
 
 	if (regs == NULL)
 		return 0;
+	local_irq_save(flags);
 	if (f->reg_idx >= sizeof(struct pt_regs) / sizeof(__u32))
 		f->reg_idx = 0;
-	return *(ptr + f->reg_idx++);
+	ptr += f->reg_idx++;
+	local_irq_restore(flags);
+	return *ptr;
 }
 
 void add_interrupt_randomness(int irq, int irq_flags)