On Thu, Mar 06, 2014 at 08:20:23AM +0000, Michael S. Tsirkin wrote:
> On Wed, Mar 05, 2014 at 05:41:28PM -0500, Christopher Covington wrote:
> > Without this, the following scenario is incorrectly determined
> > to be invalid.
> >
> > addr 0x7f_ffffe000 size 8192 addr_limit 0x80_00000000
> >
> > This behavior was observed while trying to vmsplice the stack
> > as part of a CRIU dump of a process.
> >
> > Signed-off-by: Christopher Covington <[email protected]>
> > ---
> > arch/arm64/include/asm/uaccess.h | 8 ++++----
> > 1 file changed, 4 insertions(+), 4 deletions(-)
> >
> > diff --git a/arch/arm64/include/asm/uaccess.h
> > b/arch/arm64/include/asm/uaccess.h
> > index edb3d5c..9309024 100644
> > --- a/arch/arm64/include/asm/uaccess.h
> > +++ b/arch/arm64/include/asm/uaccess.h
> > @@ -66,12 +66,12 @@ static inline void set_fs(mm_segment_t fs)
> > #define segment_eq(a,b) ((a) == (b))
> >
> > /*
> > - * Return 1 if addr < current->addr_limit, 0 otherwise.
> > + * Return 1 if addr <= current->addr_limit, 0 otherwise.
> > */
> > #define __addr_ok(addr)
> > \
> > ({ \
> > unsigned long flag; \
> > - asm("cmp %1, %0; cset %0, lo" \
> > + asm("cmp %1, %0; cset %0, ls" \
> > : "=&r" (flag) \
> > : "r" (addr), "0" (current_thread_info()->addr_limit) \
> > : "cc"); \
I don't think this is correct, since __addr_ok will now return true for
TASK_SIZE_64.
> BTW can this use mov %0, #0 like arch/arm/include/asm/uaccess.h does?
> Would make it more portable ...
How/why should this be made portable?
> > @@ -83,7 +83,7 @@ static inline void set_fs(mm_segment_t fs)
> > * Returns 1 if the range is valid, 0 otherwise.
> > *
> > * This is equivalent to the following test:
> > - * (u65)addr + (u65)size < (u65)current->addr_limit
> > + * (u65)addr + (u65)size <= current->addr_limit
> > *
> > * This needs 65-bit arithmetic.
> > */
> > @@ -91,7 +91,7 @@ static inline void set_fs(mm_segment_t fs)
> > ({ \
> > unsigned long flag, roksum; \
> > __chk_user_ptr(addr); \
> > - asm("adds %1, %1, %3; ccmp %1, %4, #2, cc; cset %0, cc" \
> > + asm("adds %1, %1, %3; ccmp %1, %4, #3, cc; cset %0, ls" \
> > : "=&r" (flag), "=&r" (roksum) \
> > : "1" (addr), "Ir" (size), \
> > "r" (current_thread_info()->addr_limit) \
Can't you just pass current_thread_info()->addr_limit) - 1 here and be done
with it?
Will
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