From mboxrd@z Thu Jan 1 00:00:00 1970 From: David Miller Date: Fri, 19 Feb 2010 23:20:11 +0000 Subject: Re: Execution possible in non-executable mappings in recent 2.6 Message-Id: <20100219.152011.32519652.davem@davemloft.net> List-Id: References: <20100219225724.GA29861@grsecurity.net> In-Reply-To: <20100219225724.GA29861@grsecurity.net> MIME-Version: 1.0 Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit To: sparclinux@vger.kernel.org Here's the fix, thanks again for the report: sparc64: Fix sun4u execute bit check in TSB I-TLB load. Thanks to testcase and report from Brad Spengler: -------------------- #include typedef int (* _wee)(void); int main(void) { char buf[8] = { '\x81', '\xc7', '\xe0', '\x08', '\x81', '\xe8', '\x00', '\x00' }; _wee wee; printf("%p\n", &buf); wee = (_wee)&buf; wee(); return 0; } -------------------- TSB I-tlb load code tries to use andcc to check the _PAGE_EXEC_4U bit, but that's bit 12 so it gets sign extended all the way up to bit 63 and the test nearly always passes as a result. Use sethi to fix the bug. Signed-off-by: David S. Miller --- arch/sparc/kernel/tsb.S | 6 ++++-- 1 files changed, 4 insertions(+), 2 deletions(-) diff --git a/arch/sparc/kernel/tsb.S b/arch/sparc/kernel/tsb.S index 8c91d9b..db15d12 100644 --- a/arch/sparc/kernel/tsb.S +++ b/arch/sparc/kernel/tsb.S @@ -191,10 +191,12 @@ tsb_dtlb_load: tsb_itlb_load: /* Executable bit must be set. */ -661: andcc %g5, _PAGE_EXEC_4U, %g0 - .section .sun4v_1insn_patch, "ax" +661: sethi %hi(_PAGE_EXEC_4U), %g4 + andcc %g5, %g4, %g0 + .section .sun4v_2insn_patch, "ax" .word 661b andcc %g5, _PAGE_EXEC_4V, %g0 + nop .previous be,pn %xcc, tsb_do_fault -- 1.6.6.1