lkml.org 
[lkml]   [2014]   [Jul]   [18]   [last100]   RSS Feed
Views: [wrap][no wrap]   [headers]  [forward] 
 
Messages in this thread
Patch in this message
/
From
Subject[PATCH] x86, vdso: Fix vdso2c's special_pages error checking
Date
Stephen Rothwell's compiler did something amazing: it unrolled a
loop, discovered that one iteration of that loop contained an
always-true test, and emitted a warning that will IMO only serve to
convince people to disable the warning.

That bogus warning caused me to wonder what prompted such an
absurdity from his compiler, and I discovered that the code in
question was, in fact, completely wrong -- I was looking things up
in the wrong array.

This affects 3.16 as well, but the only effect is to screw up the
error checking a bit. vdso2c's output is unaffected.

Signed-off-by: Andy Lutomirski <luto@amacapital.net>
---
arch/x86/vdso/vdso2c.h | 12 +++++++-----
1 file changed, 7 insertions(+), 5 deletions(-)

diff --git a/arch/x86/vdso/vdso2c.h b/arch/x86/vdso/vdso2c.h
index fd57829..0224987 100644
--- a/arch/x86/vdso/vdso2c.h
+++ b/arch/x86/vdso/vdso2c.h
@@ -109,16 +109,18 @@ static void BITSFUNC(go)(void *raw_addr, size_t raw_len,

/* Validate mapping addresses. */
for (i = 0; i < sizeof(special_pages) / sizeof(special_pages[0]); i++) {
- if (!syms[i])
+ INT_BITS symval = syms[special_pages[i]];
+
+ if (!symval)
continue; /* The mapping isn't used; ignore it. */

- if (syms[i] % 4096)
+ if (symval % 4096)
fail("%s must be a multiple of 4096\n",
required_syms[i].name);
- if (syms[sym_vvar_start] > syms[i] + 4096)
- fail("%s underruns begin_vvar\n",
+ if (symval + 4096 < syms[sym_vvar_start])
+ fail("%s underruns vvar_start\n",
required_syms[i].name);
- if (syms[i] + 4096 > 0)
+ if (symval + 4096 > 0)
fail("%s is on the wrong side of the vdso text\n",
required_syms[i].name);
}
--
1.9.3


\
 
 \ /
  Last update: 2014-07-18 20:01    [W:0.188 / U:0.004 seconds]
©2003-2020 Jasper Spaans|hosted at Digital Ocean and TransIP|Read the blog|Advertise on this site