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| author | H. Peter Anvin <hpa@linux.intel.com> | 2010-09-14 21:42:41 +0200 |
|---|---|---|
| committer | H. Peter Anvin <hpa@linux.intel.com> | 2010-09-15 01:08:46 +0200 |
| commit | 36d001c70d8a0144ac1d038f6876c484849a74de (patch) | |
| tree | 98e061ce49af5ce48d6d67ffe5d3258563f4445d /arch/x86/ia32/ia32entry.S | |
| parent | compat: Make compat_alloc_user_space() incorporate the access_ok() (diff) | |
| download | linux-36d001c70d8a0144ac1d038f6876c484849a74de.tar.xz linux-36d001c70d8a0144ac1d038f6876c484849a74de.zip | |
x86-64, compat: Test %rax for the syscall number, not %eax
On 64 bits, we always, by necessity, jump through the system call
table via %rax. For 32-bit system calls, in theory the system call
number is stored in %eax, and the code was testing %eax for a valid
system call number. At one point we loaded the stored value back from
the stack to enforce zero-extension, but that was removed in checkin
d4d67150165df8bf1cc05e532f6efca96f907cab. An actual 32-bit process
will not be able to introduce a non-zero-extended number, but it can
happen via ptrace.
Instead of re-introducing the zero-extension, test what we are
actually going to use, i.e. %rax. This only adds a handful of REX
prefixes to the code.
Reported-by: Ben Hawkes <hawkes@sota.gen.nz>
Signed-off-by: H. Peter Anvin <hpa@linux.intel.com>
Cc: <stable@kernel.org>
Cc: Roland McGrath <roland@redhat.com>
Cc: Andrew Morton <akpm@linux-foundation.org>
Diffstat (limited to 'arch/x86/ia32/ia32entry.S')
| -rw-r--r-- | arch/x86/ia32/ia32entry.S | 14 |
1 files changed, 7 insertions, 7 deletions
diff --git a/arch/x86/ia32/ia32entry.S b/arch/x86/ia32/ia32entry.S index b86feabed69b..84e3a4ef9719 100644 --- a/arch/x86/ia32/ia32entry.S +++ b/arch/x86/ia32/ia32entry.S @@ -153,7 +153,7 @@ ENTRY(ia32_sysenter_target) testl $_TIF_WORK_SYSCALL_ENTRY,TI_flags(%r10) CFI_REMEMBER_STATE jnz sysenter_tracesys - cmpl $(IA32_NR_syscalls-1),%eax + cmpq $(IA32_NR_syscalls-1),%rax ja ia32_badsys sysenter_do_call: IA32_ARG_FIXUP @@ -195,7 +195,7 @@ sysexit_from_sys_call: movl $AUDIT_ARCH_I386,%edi /* 1st arg: audit arch */ call audit_syscall_entry movl RAX-ARGOFFSET(%rsp),%eax /* reload syscall number */ - cmpl $(IA32_NR_syscalls-1),%eax + cmpq $(IA32_NR_syscalls-1),%rax ja ia32_badsys movl %ebx,%edi /* reload 1st syscall arg */ movl RCX-ARGOFFSET(%rsp),%esi /* reload 2nd syscall arg */ @@ -248,7 +248,7 @@ sysenter_tracesys: call syscall_trace_enter LOAD_ARGS32 ARGOFFSET /* reload args from stack in case ptrace changed it */ RESTORE_REST - cmpl $(IA32_NR_syscalls-1),%eax + cmpq $(IA32_NR_syscalls-1),%rax ja int_ret_from_sys_call /* sysenter_tracesys has set RAX(%rsp) */ jmp sysenter_do_call CFI_ENDPROC @@ -314,7 +314,7 @@ ENTRY(ia32_cstar_target) testl $_TIF_WORK_SYSCALL_ENTRY,TI_flags(%r10) CFI_REMEMBER_STATE jnz cstar_tracesys - cmpl $IA32_NR_syscalls-1,%eax + cmpq $IA32_NR_syscalls-1,%rax ja ia32_badsys cstar_do_call: IA32_ARG_FIXUP 1 @@ -367,7 +367,7 @@ cstar_tracesys: LOAD_ARGS32 ARGOFFSET, 1 /* reload args from stack in case ptrace changed it */ RESTORE_REST xchgl %ebp,%r9d - cmpl $(IA32_NR_syscalls-1),%eax + cmpq $(IA32_NR_syscalls-1),%rax ja int_ret_from_sys_call /* cstar_tracesys has set RAX(%rsp) */ jmp cstar_do_call END(ia32_cstar_target) @@ -425,7 +425,7 @@ ENTRY(ia32_syscall) orl $TS_COMPAT,TI_status(%r10) testl $_TIF_WORK_SYSCALL_ENTRY,TI_flags(%r10) jnz ia32_tracesys - cmpl $(IA32_NR_syscalls-1),%eax + cmpq $(IA32_NR_syscalls-1),%rax ja ia32_badsys ia32_do_call: IA32_ARG_FIXUP @@ -444,7 +444,7 @@ ia32_tracesys: call syscall_trace_enter LOAD_ARGS32 ARGOFFSET /* reload args from stack in case ptrace changed it */ RESTORE_REST - cmpl $(IA32_NR_syscalls-1),%eax + cmpq $(IA32_NR_syscalls-1),%rax ja int_ret_from_sys_call /* ia32_tracesys has set RAX(%rsp) */ jmp ia32_do_call END(ia32_syscall) |