metag/usercopy: Add early abort to copy_to_user
When copying to userland on Meta, if any faults are encountered
immediately abort the copy instead of continuing on and repeatedly
faulting, and worse potentially copying further bytes successfully to
subsequent valid pages.
Fixes: 373cd784d0fc ("metag: Memory handling")
Reported-by: Al Viro <viro@zeniv.linux.org.uk>
Signed-off-by: James Hogan <james.hogan@imgtec.com>
Cc: linux-metag@vger.kernel.org
Cc: stable@vger.kernel.org
diff --git a/arch/metag/lib/usercopy.c b/arch/metag/lib/usercopy.c
index a6ced96..714d856 100644
--- a/arch/metag/lib/usercopy.c
+++ b/arch/metag/lib/usercopy.c
@@ -538,23 +538,31 @@
if ((unsigned long) src & 1) {
__asm_copy_to_user_1(dst, src, retn);
n--;
+ if (retn)
+ return retn + n;
}
if ((unsigned long) dst & 1) {
/* Worst case - byte copy */
while (n > 0) {
__asm_copy_to_user_1(dst, src, retn);
n--;
+ if (retn)
+ return retn + n;
}
}
if (((unsigned long) src & 2) && n >= 2) {
__asm_copy_to_user_2(dst, src, retn);
n -= 2;
+ if (retn)
+ return retn + n;
}
if ((unsigned long) dst & 2) {
/* Second worst case - word copy */
while (n >= 2) {
__asm_copy_to_user_2(dst, src, retn);
n -= 2;
+ if (retn)
+ return retn + n;
}
}
@@ -569,6 +577,8 @@
while (n >= 8) {
__asm_copy_to_user_8x64(dst, src, retn);
n -= 8;
+ if (retn)
+ return retn + n;
}
}
if (n >= RAPF_MIN_BUF_SIZE) {
@@ -581,6 +591,8 @@
while (n >= 8) {
__asm_copy_to_user_8x64(dst, src, retn);
n -= 8;
+ if (retn)
+ return retn + n;
}
}
#endif
@@ -588,11 +600,15 @@
while (n >= 16) {
__asm_copy_to_user_16(dst, src, retn);
n -= 16;
+ if (retn)
+ return retn + n;
}
while (n >= 4) {
__asm_copy_to_user_4(dst, src, retn);
n -= 4;
+ if (retn)
+ return retn + n;
}
switch (n) {
@@ -609,6 +625,10 @@
break;
}
+ /*
+ * If we get here, retn correctly reflects the number of failing
+ * bytes.
+ */
return retn;
}
EXPORT_SYMBOL(__copy_user);
