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Merge branch 'cb/grep-fallback-failing-jit'

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In an environment where dynamically generated code is prohibited to
run (e.g. SELinux), failure to JIT pcre patterns is expected.  Fall
back to interpreted execution in such a case.

* cb/grep-fallback-failing-jit:
  grep: fall back to interpreter if JIT memory allocation fails
This commit is contained in:
Junio C Hamano 2023-02-15 17:11:51 -08:00
commit 214242a6ab
1 changed files with 48 additions and 2 deletions
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50
grep.c
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@ -262,6 +262,31 @@ static void pcre2_free(void *pointer, MAYBE_UNUSED void *memory_data)
free(pointer);
}
static int pcre2_jit_functional(void)
{
static int jit_working = -1;
pcre2_code *code;
size_t off;
int err;
if (jit_working != -1)
return jit_working;
/*
* Try to JIT compile a simple pattern to probe if the JIT is
* working in general. It might fail for systems where creating
* memory mappings for runtime code generation is restricted.
*/
code = pcre2_compile((PCRE2_SPTR)".", 1, 0, &err, &off, NULL);
if (!code)
return 0;
jit_working = pcre2_jit_compile(code, PCRE2_JIT_COMPLETE) == 0;
pcre2_code_free(code);
return jit_working;
}
static void compile_pcre2_pattern(struct grep_pat *p, const struct grep_opt *opt)
{
int error;
@ -317,8 +342,29 @@ static void compile_pcre2_pattern(struct grep_pat *p, const struct grep_opt *opt
pcre2_config(PCRE2_CONFIG_JIT, &p->pcre2_jit_on);
if (p->pcre2_jit_on) {
jitret = pcre2_jit_compile(p->pcre2_pattern, PCRE2_JIT_COMPLETE);
if (jitret)
die("Couldn't JIT the PCRE2 pattern '%s', got '%d'\n", p->pattern, jitret);
if (jitret == PCRE2_ERROR_NOMEMORY && !pcre2_jit_functional()) {
/*
* Even though pcre2_config(PCRE2_CONFIG_JIT, ...)
* indicated JIT support, the library might still
* fail to generate JIT code for various reasons,
* e.g. when SELinux's 'deny_execmem' or PaX's
* MPROTECT prevent creating W|X memory mappings.
*
* Instead of faling hard, fall back to interpreter
* mode, just as if the pattern was prefixed with
* '(*NO_JIT)'.
*/
p->pcre2_jit_on = 0;
return;
} else if (jitret) {
int need_clip = p->patternlen > 64;
int clip_len = need_clip ? 64 : p->patternlen;
die("Couldn't JIT the PCRE2 pattern '%.*s'%s, got '%d'%s",
clip_len, p->pattern, need_clip ? "..." : "", jitret,
pcre2_jit_functional()
? "\nPerhaps prefix (*NO_JIT) to your pattern?"
: "");
}
/*
* The pcre2_config(PCRE2_CONFIG_JIT, ...) call just