Messages in this thread |  | | Date | Wed, 06 Feb 2013 18:36:38 +0800 | From | Chen Gang <> | Subject | Re: [PATCH] kernel: arg2 is unsigned long which is never < 0 |
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于 2013年02月06日 16:56, Cyrill Gorcunov 写道: > On Wed, Feb 06, 2013 at 04:44:35PM +0800, Chen Gang wrote: >> > >> > diff --git a/kernel/sys.c b/kernel/sys.c >> > index 24d1ef5..568b9ca 100644 >> > --- a/kernel/sys.c >> > +++ b/kernel/sys.c >> > @@ -2027,7 +2027,7 @@ SYSCALL_DEFINE5(prctl, int, option, unsigned long, arg2, unsigned long, arg3, >> > error = get_dumpable(me->mm); >> > break; >> > case PR_SET_DUMPABLE: >> > - if (arg2 < 0 || arg2 > 1) { >> > + if (arg2 > 1) { >> > error = -EINVAL; >> > break; >> > } > I guess > > if (arg2 != SUID_DUMPABLE_DISABLED && > arg2 != SUID_DUMPABLE_ENABLED) { > error = -EINVAL; > break; > } > > would be better. Still, current patch looks good to me.
thank you for your suggestion, firstly.
and after read more, it seems a little more complex: for me, I think it would be better:
if (arg2 != SUID_DUMP_DISABLE && arg2 != SUID_DUMP_USER) { error = -EINVAL; break; }
the reason is below:
it has 2 branches:
branch 1:
#define SUID_DUMP_DISABLE 0 /* No setuid dumping */ #define SUID_DUMP_USER 1 /* Dump as user of process */ #define SUID_DUMP_ROOT 2 /* Dump as root */
in patch d6e711448137ca3301512cec41a2c2ce852b3d0a Signed-of-by Alan Cox in 2005. define these constant for using. change 2 choices to 3 choices (add a new choice).
in patch abf75a5033d4da7b8a7e92321d74021d1fcfb502 Signed-of-by Marcel Holtmann in 2006. find and fix a security issue for it.
branch 2:
#define SUID_DUMPABLE_DISABLED 0 #define SUID_DUMPABLE_ENABLED 1 #define SUID_DUMPABLE_SAFE 2
in patch 54b501992dd2a839e94e76aa392c392b55080ce8 Signed-of-by Kees Cook in Jul 30 2012 define the constants for using print warning when detect unsafe core_pattern settings
in patch 0f4cfb2e4e7a7e4e97a3e90e2ba1062f07fb2cb1 Signed-of-by Oleg Nesterov in Oct 4 2012 use SUID_DUMPABLE_ENABLED rather than hardcoded 1
analysing: branch 1 and branch 2 have the same values with different macro names. branch 1 is much older than branch 2. for features: branch 1 is for functional feature and bug fix, branch 2 is for printing warning and beautifying code.
it seems: branch 2 did not notice the branch 1, before it performs. if it noticed, it is meanless to define the new macros.
result: still use the macros of branch 1 and use branch 1 macros instead of branch 2 macros (need an additional patch).
:-)
Regards.
-- Chen Gang
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