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authorJames Hogan <james.hogan@imgtec.com>2017-03-31 13:35:01 +0100
committerJames Hogan <james.hogan@imgtec.com>2017-04-05 14:49:42 +0100
commitfb8ea062a8f2e85256e13f55696c5c5f0dfdcc8b (patch)
tree263488d227fe8bb0dea7749a07d45de104c62bd9 /arch
parent2257211942bbbf6c798ab70b487d7e62f7835a1a (diff)
downloadlwn-fb8ea062a8f2e85256e13f55696c5c5f0dfdcc8b.tar.gz
lwn-fb8ea062a8f2e85256e13f55696c5c5f0dfdcc8b.zip
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
Diffstat (limited to 'arch')
-rw-r--r--arch/metag/lib/usercopy.c20
1 files changed, 20 insertions, 0 deletions
diff --git a/arch/metag/lib/usercopy.c b/arch/metag/lib/usercopy.c
index a6ced9691ddb..714d8562aa20 100644
--- a/arch/metag/lib/usercopy.c
+++ b/arch/metag/lib/usercopy.c
@@ -538,23 +538,31 @@ unsigned long __copy_user(void __user *pdst, const void *psrc,
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 @@ unsigned long __copy_user(void __user *pdst, const void *psrc,
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 @@ unsigned long __copy_user(void __user *pdst, const void *psrc,
while (n >= 8) {
__asm_copy_to_user_8x64(dst, src, retn);
n -= 8;
+ if (retn)
+ return retn + n;
}
}
#endif
@@ -588,11 +600,15 @@ unsigned long __copy_user(void __user *pdst, const void *psrc,
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 @@ unsigned long __copy_user(void __user *pdst, const void *psrc,
break;
}
+ /*
+ * If we get here, retn correctly reflects the number of failing
+ * bytes.
+ */
return retn;
}
EXPORT_SYMBOL(__copy_user);