From: Vineet Gupta Date: Fri, 19 Aug 2016 19:10:02 +0000 (-0700) Subject: ARC: uaccess: get_user to zero out dest in cause of fault X-Git-Tag: firefly_0821_release~176^2~4^2~28^2~22 X-Git-Url: http://demsky.eecs.uci.edu/git/?a=commitdiff_plain;h=59a2d6b2a6851435a34a7f42a1082367ac8296f0;p=firefly-linux-kernel-4.4.55.git ARC: uaccess: get_user to zero out dest in cause of fault commit 05d9d0b96e53c52a113fd783c0c97c830c8dc7af upstream. Al reported potential issue with ARC get_user() as it wasn't clearing out destination pointer in case of fault due to bad address etc. Verified using following | { | u32 bogus1 = 0xdeadbeef; | u64 bogus2 = 0xdead; | int rc1, rc2; | | pr_info("Orig values %x %llx\n", bogus1, bogus2); | rc1 = get_user(bogus1, (u32 __user *)0x40000000); | rc2 = get_user(bogus2, (u64 __user *)0x50000000); | pr_info("access %d %d, new values %x %llx\n", | rc1, rc2, bogus1, bogus2); | } | [ARCLinux]# insmod /mnt/kernel-module/qtn.ko | Orig values deadbeef dead | access -14 -14, new values 0 0 Reported-by: Al Viro Cc: Linus Torvalds Cc: linux-snps-arc@lists.infradead.org Cc: linux-kernel@vger.kernel.org Signed-off-by: Vineet Gupta Signed-off-by: Al Viro Signed-off-by: Greg Kroah-Hartman --- diff --git a/arch/arc/include/asm/uaccess.h b/arch/arc/include/asm/uaccess.h index d1da6032b715..d4d8df706efa 100644 --- a/arch/arc/include/asm/uaccess.h +++ b/arch/arc/include/asm/uaccess.h @@ -83,7 +83,10 @@ "2: ;nop\n" \ " .section .fixup, \"ax\"\n" \ " .align 4\n" \ - "3: mov %0, %3\n" \ + "3: # return -EFAULT\n" \ + " mov %0, %3\n" \ + " # zero out dst ptr\n" \ + " mov %1, 0\n" \ " j 2b\n" \ " .previous\n" \ " .section __ex_table, \"a\"\n" \ @@ -101,7 +104,11 @@ "2: ;nop\n" \ " .section .fixup, \"ax\"\n" \ " .align 4\n" \ - "3: mov %0, %3\n" \ + "3: # return -EFAULT\n" \ + " mov %0, %3\n" \ + " # zero out dst ptr\n" \ + " mov %1, 0\n" \ + " mov %R1, 0\n" \ " j 2b\n" \ " .previous\n" \ " .section __ex_table, \"a\"\n" \