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metag/usercopy: Add early abort to copy_to_user

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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: 373cd784d0 ("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
This commit is contained in:
James Hogan 2017-03-31 13:35:01 +01:00
parent 2257211942
commit fb8ea062a8
1 changed files with 20 additions and 0 deletions
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20
arch/metag/lib/usercopy.c
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@ -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);