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x86, smap: Do not abuse the [f][x]rstor_checking() functions for user space 

With SMAP, the [f][x]rstor_checking() functions are no longer usable
for user-space pointers by applying a simple __force cast.  Instead,
create new [f][x]rstor_user() functions which do the proper SMAP
magic.

Signed-off-by: H. Peter Anvin <hpa@linux.intel.com>
Cc: Suresh Siddha <suresh.b.siddha@intel.com>
Link: http://lkml.kernel.org/r/1343171129-2747-3-git-send-email-suresh.b.siddha@intel.com
This commit is contained in:
H. Peter Anvin 2012-09-25 15:42:18 -07:00
parent 49b8c695e3
commit e139e95590
2 changed files with 20 additions and 3 deletions
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17
arch/x86/include/asm/fpu-internal.h
View File

@ -181,11 +181,28 @@ static inline int fxrstor_checking(struct i387_fxsave_struct *fx)
"m" (*fx));
}
static inline int fxrstor_user(struct i387_fxsave_struct __user *fx)
{
if (config_enabled(CONFIG_X86_32))
return user_insn(fxrstor %[fx], "=m" (*fx), [fx] "m" (*fx));
else if (config_enabled(CONFIG_AS_FXSAVEQ))
return user_insn(fxrstorq %[fx], "=m" (*fx), [fx] "m" (*fx));
/* See comment in fpu_fxsave() below. */
return user_insn(rex64/fxrstor (%[fx]), "=m" (*fx), [fx] "R" (fx),
"m" (*fx));
}
static inline int frstor_checking(struct i387_fsave_struct *fx)
{
return check_insn(frstor %[fx], "=m" (*fx), [fx] "m" (*fx));
}
static inline int frstor_user(struct i387_fsave_struct __user *fx)
{
return user_insn(frstor %[fx], "=m" (*fx), [fx] "m" (*fx));
}
static inline void fpu_fxsave(struct fpu *fpu)
{
if (config_enabled(CONFIG_X86_32))

6
arch/x86/kernel/xsave.c
View File

@ -315,7 +315,7 @@ static inline int restore_user_xstate(void __user *buf, u64 xbv, int fx_only)
if ((unsigned long)buf % 64 || fx_only) {
u64 init_bv = pcntxt_mask & ~XSTATE_FPSSE;
xrstor_state(init_xstate_buf, init_bv);
return fxrstor_checking((__force void *) buf);
return fxrstor_user(buf);
} else {
u64 init_bv = pcntxt_mask & ~xbv;
if (unlikely(init_bv))
@ -323,9 +323,9 @@ static inline int restore_user_xstate(void __user *buf, u64 xbv, int fx_only)
return xrestore_user(buf, xbv);
}
} else if (use_fxsr()) {
return fxrstor_checking((__force void *) buf);
return fxrstor_user(buf);
} else
return frstor_checking((__force void *) buf);
return frstor_user(buf);
}
int __restore_xstate_sig(void __user *buf, void __user *buf_fx, int size)