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100 lines
3.5 KiB
100 lines
3.5 KiB
From: H. Peter Anvin <hpa@linux.intel.com>
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Date: Tue, 14 Sep 2010 19:42:41 +0000 (-0700)
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Subject: x86-64, compat: Test %rax for the syscall number, not %eax
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Git-commit: 36d001c70d8a0144ac1d038f6876c484849a74de
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References: CVE-2010-3301 bnc#639708
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Patch-mainline: 2.6.36
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Introduced-by: 2.6.27
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x86-64, compat: Test %rax for the syscall number, not %eax
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On 64 bits, we always, by necessity, jump through the system call
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table via %rax. For 32-bit system calls, in theory the system call
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number is stored in %eax, and the code was testing %eax for a valid
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system call number. At one point we loaded the stored value back from
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the stack to enforce zero-extension, but that was removed in checkin
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d4d67150165df8bf1cc05e532f6efca96f907cab. An actual 32-bit process
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will not be able to introduce a non-zero-extended number, but it can
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happen via ptrace.
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Instead of re-introducing the zero-extension, test what we are
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actually going to use, i.e. %rax. This only adds a handful of REX
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prefixes to the code.
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Reported-by: Ben Hawkes <hawkes@sota.gen.nz>
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Signed-off-by: H. Peter Anvin <hpa@linux.intel.com>
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Cc: <stable@kernel.org>
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Cc: Roland McGrath <roland@redhat.com>
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Cc: Andrew Morton <akpm@linux-foundation.org>
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Acked-by: Jeff Mahoney <jeffm@suse.com>
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---
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arch/x86/ia32/ia32entry.S | 14 +++++++-------
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1 file changed, 7 insertions(+), 7 deletions(-)
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--- a/arch/x86/ia32/ia32entry.S
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+++ b/arch/x86/ia32/ia32entry.S
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@@ -159,7 +159,7 @@ ENTRY(ia32_sysenter_target)
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testl $_TIF_WORK_SYSCALL_ENTRY,TI_flags(%r10)
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CFI_REMEMBER_STATE
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jnz sysenter_tracesys
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- cmpl $(IA32_NR_syscalls-1),%eax
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+ cmpq $(IA32_NR_syscalls-1),%rax
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ja ia32_badsys
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sysenter_do_call:
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IA32_ARG_FIXUP
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@@ -201,7 +201,7 @@ sysexit_from_sys_call:
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movl $AUDIT_ARCH_I386,%edi /* 1st arg: audit arch */
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call audit_syscall_entry
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movl RAX-ARGOFFSET(%rsp),%eax /* reload syscall number */
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- cmpl $(IA32_NR_syscalls-1),%eax
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+ cmpq $(IA32_NR_syscalls-1),%rax
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ja ia32_badsys
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movl %ebx,%edi /* reload 1st syscall arg */
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movl RCX-ARGOFFSET(%rsp),%esi /* reload 2nd syscall arg */
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@@ -254,7 +254,7 @@ sysenter_tracesys:
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call syscall_trace_enter
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LOAD_ARGS32 ARGOFFSET /* reload args from stack in case ptrace changed it */
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RESTORE_REST
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- cmpl $(IA32_NR_syscalls-1),%eax
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+ cmpq $(IA32_NR_syscalls-1),%rax
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ja int_ret_from_sys_call /* sysenter_tracesys has set RAX(%rsp) */
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jmp sysenter_do_call
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CFI_ENDPROC
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@@ -320,7 +320,7 @@ ENTRY(ia32_cstar_target)
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testl $_TIF_WORK_SYSCALL_ENTRY,TI_flags(%r10)
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CFI_REMEMBER_STATE
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jnz cstar_tracesys
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- cmpl $IA32_NR_syscalls-1,%eax
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+ cmpq $IA32_NR_syscalls-1,%rax
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ja ia32_badsys
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cstar_do_call:
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IA32_ARG_FIXUP 1
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@@ -373,7 +373,7 @@ cstar_tracesys:
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LOAD_ARGS32 ARGOFFSET, 1 /* reload args from stack in case ptrace changed it */
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RESTORE_REST
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xchgl %ebp,%r9d
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- cmpl $(IA32_NR_syscalls-1),%eax
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+ cmpq $(IA32_NR_syscalls-1),%rax
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ja int_ret_from_sys_call /* cstar_tracesys has set RAX(%rsp) */
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jmp cstar_do_call
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END(ia32_cstar_target)
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@@ -431,7 +431,7 @@ ENTRY(ia32_syscall)
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orl $TS_COMPAT,TI_status(%r10)
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testl $_TIF_WORK_SYSCALL_ENTRY,TI_flags(%r10)
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jnz ia32_tracesys
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- cmpl $(IA32_NR_syscalls-1),%eax
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+ cmpq $(IA32_NR_syscalls-1),%rax
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ja ia32_badsys
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ia32_do_call:
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IA32_ARG_FIXUP
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@@ -450,7 +450,7 @@ ia32_tracesys:
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call syscall_trace_enter
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LOAD_ARGS32 ARGOFFSET /* reload args from stack in case ptrace changed it */
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RESTORE_REST
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- cmpl $(IA32_NR_syscalls-1),%eax
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+ cmpq $(IA32_NR_syscalls-1),%rax
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ja int_ret_from_sys_call /* ia32_tracesys has set RAX(%rsp) */
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jmp ia32_do_call
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END(ia32_syscall)
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