x86-64, compat: Retruncate rax after ia32 syscall entry tracing

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In commit d4d6715, we reopened an old hole for a 64-bit ptracer touching a
32-bit tracee in system call entry.  A %rax value set via ptrace at the
entry tracing stop gets used whole as a 32-bit syscall number, while we
only check the low 32 bits for validity.

Fix it by truncating %rax back to 32 bits after syscall_trace_enter,
in addition to testing the full 64 bits as has already been added.

Reported-by: Ben Hawkes <hawkes@sota.gen.nz>
Signed-off-by: Roland McGrath <roland@redhat.com>
Signed-off-by: H. Peter Anvin <hpa@linux.intel.com>

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Roland McGrath 2010-09-14 12:22:58 -07:00 • committed by H. Peter Anvin

parent 36d001c70d

commit eefdca043e

1 changed files with 7 additions and 1 deletions

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arch/x86/ia32/ia32entry.S

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