Patchwork powerpc: fix personality handling in ppc64_personality()

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Submitter Jiri Kosina
Date Aug. 1, 2012, 8:03 p.m.
Message ID <alpine.LNX.2.00.1208012201520.14910@pobox.suse.cz>
Download mbox | patch
Permalink /patch/174585/
State Superseded
Headers show

Comments

Jiri Kosina - Aug. 1, 2012, 8:03 p.m.
Directly comparing current->personality against PER_LINUX32 doesn't work 
in cases when any of the personality flags stored in the top three bytes 
are used.

Directly forcefully setting personality to PER_LINUX32 or PER_LINUX
discards any flags stored in the top three bytes

Use personality() macro to compare only PER_MASK bytes and make sure that
we are setting only the bits that should be set, instead of
overwriting the whole value.

Signed-off-by: Jiri Kosina <jkosina@suse.cz>
---

Found accidentally. Untested, I don't have the hardware.

 arch/powerpc/kernel/syscalls.c |    8 ++++----
 1 files changed, 4 insertions(+), 4 deletions(-)
Andreas Schwab - Aug. 1, 2012, 10:19 p.m.
Jiri Kosina <jkosina@suse.cz> writes:

>  	if (personality(current->personality) == PER_LINUX32
> -	    && personality == PER_LINUX)
> -		personality = PER_LINUX32;
> +	    && personality(personality) == PER_LINUX)
> +		personality &= ~PER_LINUX | PER_LINUX32;

That doesn't work.  ~PER_LINUX is -1, so this is a no-op.

>  	ret = sys_personality(personality);
> -	if (ret == PER_LINUX32)
> -		ret = PER_LINUX;
> +	if (personality(ret) == PER_LINUX32)
> +		ret &= ~PER_LINUX32 | PER_LINUX;

That only "works" because PER_LINUX is 0.

Andreas.

Patch

diff --git a/arch/powerpc/kernel/syscalls.c b/arch/powerpc/kernel/syscalls.c
index f2496f2..4dcc7c6 100644
--- a/arch/powerpc/kernel/syscalls.c
+++ b/arch/powerpc/kernel/syscalls.c
@@ -107,11 +107,11 @@  long ppc64_personality(unsigned long personality)
 	long ret;
 
 	if (personality(current->personality) == PER_LINUX32
-	    && personality == PER_LINUX)
-		personality = PER_LINUX32;
+	    && personality(personality) == PER_LINUX)
+		personality &= ~PER_LINUX | PER_LINUX32;
 	ret = sys_personality(personality);
-	if (ret == PER_LINUX32)
-		ret = PER_LINUX;
+	if (personality(ret) == PER_LINUX32)
+		ret &= ~PER_LINUX32 | PER_LINUX;
 	return ret;
 }
 #endif