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Commit fb8ea062 authored by James Hogan's avatar James Hogan
Browse files

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: 373cd784 ("metag: Memory handling")
Reported-by: default avatarAl Viro <viro@zeniv.linux.org.uk>
Signed-off-by: default avatarJames Hogan <james.hogan@imgtec.com>
Cc: linux-metag@vger.kernel.org
Cc: stable@vger.kernel.org
parent 22572119

arch/metag/lib/usercopy.c

+20 −0
Original line number Diff line number Diff line
@@ -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);