From: Will Deacon <will.deacon@arm.com>
Date: Fri, 22 Aug 2014 13:20:24 +0000 (+0100)
Subject: arm64: ptrace: fix compat reg getter/setter return values
X-Git-Tag: v3.17-rc4~30^2~5
X-Git-Url: https://asedeno.scripts.mit.edu/gitweb/?a=commitdiff_plain;h=85487edd252fa04718dcd735bc0f41213bbb9546;p=linux.git

arm64: ptrace: fix compat reg getter/setter return values

copy_{to,from}_user return the number of bytes remaining on failure, not
an error code.

This patch returns -EFAULT when the copy operation didn't complete,
rather than expose the number of bytes not copied directly to userspace.

Signed-off-by: Will Deacon <will.deacon@arm.com>
---

diff --git a/arch/arm64/kernel/ptrace.c b/arch/arm64/kernel/ptrace.c
index 2ac998878001..fe63ac5e9bf5 100644
--- a/arch/arm64/kernel/ptrace.c
+++ b/arch/arm64/kernel/ptrace.c
@@ -663,8 +663,10 @@ static int compat_gpr_get(struct task_struct *target,
 			kbuf += sizeof(reg);
 		} else {
 			ret = copy_to_user(ubuf, &reg, sizeof(reg));
-			if (ret)
+			if (ret) {
+				ret = -EFAULT;
 				break;
+			}
 
 			ubuf += sizeof(reg);
 		}
@@ -702,8 +704,10 @@ static int compat_gpr_set(struct task_struct *target,
 			kbuf += sizeof(reg);
 		} else {
 			ret = copy_from_user(&reg, ubuf, sizeof(reg));
-			if (ret)
-				return ret;
+			if (ret) {
+				ret = -EFAULT;
+				break;
+			}
 
 			ubuf += sizeof(reg);
 		}