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| author | Eric Paris <eparis@redhat.com> | 2014-10-23 00:04:03 -0400 |
|---|---|---|
| committer | H. Peter Anvin <hpa@linux.intel.com> | 2014-10-24 13:27:56 -0700 |
| commit | 26c2d2b39128adba276d140eefa2745591b88536 (patch) | |
| tree | dcd358783ebe100fae40afff3ea1cff8edb0034b | |
| parent | db65bcfd9563a7531c3dd46c350565705be1fd84 (diff) | |
| download | linux-26c2d2b39128adba276d140eefa2745591b88536.tar.gz linux-26c2d2b39128adba276d140eefa2745591b88536.tar.bz2 linux-26c2d2b39128adba276d140eefa2745591b88536.zip | |
i386/audit: stop scribbling on the stack frame
git commit b4f0d3755c5e9cc86292d5fd78261903b4f23d4a was very very dumb.
It was writing over %esp/pt_regs semi-randomly on i686 with the expected
"system can't boot" results. As noted in:
https://bugs.freedesktop.org/show_bug.cgi?id=85277
This patch stops fscking with pt_regs. Instead it sets up the registers
for the call to __audit_syscall_entry in the most obvious conceivable
way. It then does just a tiny tiny touch of magic. We need to get what
started in PT_EDX into 0(%esp) and PT_ESI into 4(%esp). This is as easy
as a pair of pushes.
After the call to __audit_syscall_entry all we need to do is get that
now useless junk off the stack (pair of pops) and reload %eax with the
original syscall so other stuff can keep going about it's business.
Reported-by: Paulo Zanoni <przanoni@gmail.com>
Signed-off-by: Eric Paris <eparis@redhat.com>
Link: http://lkml.kernel.org/r/1414037043-30647-1-git-send-email-eparis@redhat.com
Cc: Richard Guy Briggs <rgb@redhat.com>
Signed-off-by: H. Peter Anvin <hpa@linux.intel.com>
| -rw-r--r-- | arch/x86/kernel/entry_32.S | 15 |
1 files changed, 7 insertions, 8 deletions
diff --git a/arch/x86/kernel/entry_32.S b/arch/x86/kernel/entry_32.S index b553ed89e5f5..344b63f18d14 100644 --- a/arch/x86/kernel/entry_32.S +++ b/arch/x86/kernel/entry_32.S @@ -447,15 +447,14 @@ sysenter_exit: sysenter_audit: testl $(_TIF_WORK_SYSCALL_ENTRY & ~_TIF_SYSCALL_AUDIT),TI_flags(%ebp) jnz syscall_trace_entry - addl $4,%esp - CFI_ADJUST_CFA_OFFSET -4 - movl %esi,4(%esp) /* 5th arg: 4th syscall arg */ - movl %edx,(%esp) /* 4th arg: 3rd syscall arg */ - /* %ecx already in %ecx 3rd arg: 2nd syscall arg */ - movl %ebx,%edx /* 2nd arg: 1st syscall arg */ - /* %eax already in %eax 1st arg: syscall number */ + /* movl PT_EAX(%esp), %eax already set, syscall number: 1st arg to audit */ + movl PT_EBX(%esp), %edx /* ebx/a0: 2nd arg to audit */ + /* movl PT_ECX(%esp), %ecx already set, a1: 3nd arg to audit */ + pushl_cfi PT_ESI(%esp) /* a3: 5th arg */ + pushl_cfi PT_EDX+4(%esp) /* a2: 4th arg */ call __audit_syscall_entry - pushl_cfi %ebx + popl_cfi %ecx /* get that remapped edx off the stack */ + popl_cfi %ecx /* get that remapped esi off the stack */ movl PT_EAX(%esp),%eax /* reload syscall number */ jmp sysenter_do_call |