From 24876bf17e7c6c7c9c39a6a05aa609cba33c93a7 Mon Sep 17 00:00:00 2001 From: Alexandre Julliard Date: Thu, 12 Sep 2019 11:31:13 +0200 Subject: [PATCH] ntdll: Use virtual_uninterrupted_read_memory() to read code inside signal handler on x86-64. Signed-off-by: Alexandre Julliard --- dlls/ntdll/signal_x86_64.c | 12 +++++++----- 1 file changed, 7 insertions(+), 5 deletions(-) diff --git a/dlls/ntdll/signal_x86_64.c b/dlls/ntdll/signal_x86_64.c index feb2e69d3f3..d48f445f67b 100644 --- a/dlls/ntdll/signal_x86_64.c +++ b/dlls/ntdll/signal_x86_64.c @@ -2829,10 +2829,11 @@ static void setup_raise_exception( ucontext_t *sigcontext, EXCEPTION_RECORD *rec */ static inline DWORD is_privileged_instr( CONTEXT *context ) { - const BYTE *instr = (BYTE *)context->Rip; - unsigned int prefix_count = 0; + BYTE instr[16]; + unsigned int i, prefix_count = 0; + unsigned int len = virtual_uninterrupted_read_memory( (BYTE *)context->Rip, instr, sizeof(instr) ); - for (;;) switch(*instr) + for (i = 0; i < len; i++) switch (instr[i]) { /* instruction prefixes */ case 0x2e: /* %cs: */ @@ -2863,11 +2864,11 @@ static inline DWORD is_privileged_instr( CONTEXT *context ) case 0xf2: /* repne */ case 0xf3: /* repe */ if (++prefix_count >= 15) return EXCEPTION_ILLEGAL_INSTRUCTION; - instr++; continue; case 0x0f: /* extended instruction */ - switch(instr[1]) + if (i == len - 1) return 0; + switch (instr[i + 1]) { case 0x06: /* clts */ case 0x08: /* invd */ @@ -2899,6 +2900,7 @@ static inline DWORD is_privileged_instr( CONTEXT *context ) default: return 0; } + return 0; }