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8173848: realpath is unsafe

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Fix occurrences of realpath in hotspot to use safe POSIX.1-2008 form.

Reviewed-by: dsamersoff, dholmes, clanger
This commit is contained in:
Thomas Stuefe 2017-03-13 20:23:11 +01:00
parent 4b9562288f
commit 35d5d1c53d
6 changed files with 69 additions and 14 deletions
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2
hotspot/src/os/aix/vm/os_aix.cpp
View File

@ -1576,7 +1576,7 @@ void os::jvm_path(char *buf, jint buflen) {
Dl_info dlinfo;
int ret = dladdr(CAST_FROM_FN_PTR(void *, os::jvm_path), &dlinfo);
assert(ret != 0, "cannot locate libjvm");
char* rp = realpath((char *)dlinfo.dli_fname, buf);
char* rp = os::Posix::realpath((char *)dlinfo.dli_fname, buf, buflen);
assert(rp != NULL, "error in realpath(): maybe the 'path' argument is too long?");
strncpy(saved_jvm_path, buf, sizeof(saved_jvm_path));

8
hotspot/src/os/bsd/vm/os_bsd.cpp
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@ -1,5 +1,5 @@
/*
* Copyright (c) 1999, 2016, Oracle and/or its affiliates. All rights reserved.
* Copyright (c) 1999, 2017, Oracle and/or its affiliates. All rights reserved.
* DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
*
* This code is free software; you can redistribute it and/or modify it
@ -1754,7 +1754,7 @@ void os::jvm_path(char *buf, jint buflen) {
assert(ret, "cannot locate libjvm");
char *rp = NULL;
if (ret && dli_fname[0] != '\0') {
rp = realpath(dli_fname, buf);
rp = os::Posix::realpath(dli_fname, buf, buflen);
}
if (rp == NULL) {
return;
@ -1786,7 +1786,7 @@ void os::jvm_path(char *buf, jint buflen) {
p = strrchr(buf, '/');
assert(strstr(p, "/libjvm") == p, "invalid library name");
rp = realpath(java_home_var, buf);
rp = os::Posix::realpath(java_home_var, buf, buflen);
if (rp == NULL) {
return;
}
@ -1820,7 +1820,7 @@ void os::jvm_path(char *buf, jint buflen) {
snprintf(buf + len, buflen-len, "/libjvm%s", JNI_LIB_SUFFIX);
} else {
// Fall back to path of current library
rp = realpath(dli_fname, buf);
rp = os::Posix::realpath(dli_fname, buf, buflen);
if (rp == NULL) {
return;
}

8
hotspot/src/os/linux/vm/os_linux.cpp
View File

@ -1,5 +1,5 @@
/*
* Copyright (c) 1999, 2016, Oracle and/or its affiliates. All rights reserved.
* Copyright (c) 1999, 2017, Oracle and/or its affiliates. All rights reserved.
* DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
*
* This code is free software; you can redistribute it and/or modify it
@ -2318,7 +2318,7 @@ void os::jvm_path(char *buf, jint buflen) {
assert(ret, "cannot locate libjvm");
char *rp = NULL;
if (ret && dli_fname[0] != '\0') {
rp = realpath(dli_fname, buf);
rp = os::Posix::realpath(dli_fname, buf, buflen);
}
if (rp == NULL) {
return;
@ -2352,7 +2352,7 @@ void os::jvm_path(char *buf, jint buflen) {
}
assert(strstr(p, "/libjvm") == p, "invalid library name");
rp = realpath(java_home_var, buf);
rp = os::Posix::realpath(java_home_var, buf, buflen);
if (rp == NULL) {
return;
}
@ -2373,7 +2373,7 @@ void os::jvm_path(char *buf, jint buflen) {
snprintf(buf + len, buflen-len, "/hotspot/libjvm.so");
} else {
// Go back to path of .so
rp = realpath(dli_fname, buf);
rp = os::Posix::realpath(dli_fname, buf, buflen);
if (rp == NULL) {
return;
}

44
hotspot/src/os/posix/vm/os_posix.cpp
View File

@ -1,5 +1,5 @@
/*
* Copyright (c) 1999, 2016, Oracle and/or its affiliates. All rights reserved.
* Copyright (c) 1999, 2017, Oracle and/or its affiliates. All rights reserved.
* DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
*
* This code is free software; you can redistribute it and/or modify it
@ -1105,6 +1105,48 @@ char* os::Posix::describe_pthread_attr(char* buf, size_t buflen, const pthread_a
return buf;
}
char* os::Posix::realpath(const char* filename, char* outbuf, size_t outbuflen) {
if (filename == NULL || outbuf == NULL || outbuflen < 1) {
assert(false, "os::Posix::realpath: invalid arguments.");
errno = EINVAL;
return NULL;
}
char* result = NULL;
// This assumes platform realpath() is implemented according to POSIX.1-2008.
// POSIX.1-2008 allows to specify NULL for the output buffer, in which case
// output buffer is dynamically allocated and must be ::free()'d by the caller.
char* p = ::realpath(filename, NULL);
if (p != NULL) {
if (strlen(p) < outbuflen) {
strcpy(outbuf, p);
result = outbuf;
} else {
errno = ENAMETOOLONG;
}
::free(p); // *not* os::free
} else {
// Fallback for platforms struggling with modern Posix standards (AIX 5.3, 6.1). If realpath
// returns EINVAL, this may indicate that realpath is not POSIX.1-2008 compatible and
// that it complains about the NULL we handed down as user buffer.
// In this case, use the user provided buffer but at least check whether realpath caused
// a memory overwrite.
if (errno == EINVAL) {
outbuf[outbuflen - 1] = '\0';
p = ::realpath(filename, outbuf);
if (p != NULL) {
guarantee(outbuf[outbuflen - 1] == '\0', "realpath buffer overwrite detected.");
result = p;
}
}
}
return result;
}
// Check minimum allowable stack sizes for thread creation and to initialize
// the java system classes, including StackOverflowError - depends on page
// size.

9
hotspot/src/os/posix/vm/os_posix.hpp
View File

@ -1,5 +1,5 @@
/*
* Copyright (c) 1999, 2016, Oracle and/or its affiliates. All rights reserved.
* Copyright (c) 1999, 2017, Oracle and/or its affiliates. All rights reserved.
* DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
*
* This code is free software; you can redistribute it and/or modify it
@ -96,6 +96,13 @@ public:
// to buf with len buflen; buf is returned.
static char* describe_pthread_attr(char* buf, size_t buflen, const pthread_attr_t* attr);
// A safe implementation of realpath which will not cause a buffer overflow if the resolved path
// is longer than PATH_MAX.
// On success, returns 'outbuf', which now contains the path.
// On error, it will return NULL and set errno. The content of 'outbuf' is undefined.
// On truncation error ('outbuf' too small), it will return NULL and set errno to ENAMETOOLONG.
static char* realpath(const char* filename, char* outbuf, size_t outbuflen);
};
/*

12
hotspot/src/os/solaris/vm/os_solaris.cpp
View File

@ -2034,7 +2034,9 @@ void os::jvm_path(char *buf, jint buflen) {
int ret = dladdr(CAST_FROM_FN_PTR(void *, os::jvm_path), &dlinfo);
assert(ret != 0, "cannot locate libjvm");
if (ret != 0 && dlinfo.dli_fname != NULL) {
realpath((char *)dlinfo.dli_fname, buf);
if (os::Posix::realpath((char *)dlinfo.dli_fname, buf, buflen) == NULL) {
return;
}
} else {
buf[0] = '\0';
return;
@ -2065,7 +2067,9 @@ void os::jvm_path(char *buf, jint buflen) {
p = strrchr(buf, '/');
assert(strstr(p, "/libjvm") == p, "invalid library name");
realpath(java_home_var, buf);
if (os::Posix::realpath(java_home_var, buf, buflen) == NULL) {
return;
}
// determine if this is a legacy image or modules image
// modules image doesn't have "jre" subdirectory
len = strlen(buf);
@ -2082,7 +2086,9 @@ void os::jvm_path(char *buf, jint buflen) {
snprintf(buf + len, buflen-len, "/hotspot/libjvm.so");
} else {
// Go back to path of .so
realpath((char *)dlinfo.dli_fname, buf);
if (os::Posix::realpath((char *)dlinfo.dli_fname, buf, buflen) == NULL) {
return;
}
}
}
}