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string: strerror, strsignal cannot use buffer after dlmopen (bug 32026)

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Secondary namespaces have a different malloc.  Allocating the
buffer in one namespace and freeing it another results in
heap corruption.  Fix this by using a static string (potentially
translated) in secondary namespaces.  It would also be possible
to use the malloc from the initial namespace to manage the
buffer, but these functions would still not be safe to use in
auditors etc. because a call to strerror could still free a
buffer while it is used by the application.  Another approach
could use proper initial-exec TLS, duplicated in secondary
namespaces, but that would need a callback interface for freeing
libc resources in namespaces on thread exit, which does not exist
today.

Reviewed-by: Adhemerval Zanella <adhemerval.zanella@linaro.org>
(cherry picked from commit 25a5eb4010)
This commit is contained in:
Florian Weimer 2024-08-19 15:48:03 +02:00
parent 586e4cd8c6
commit 709319f9de
3 changed files with 46 additions and 24 deletions
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1
NEWS
View File

@ -13,6 +13,7 @@ The following bugs are resolved with this release:
[31968] mremap implementation in C does not handle arguments correctly
[31890] resolv: Allow short error responses to match any DNS query
[31968] mremap implementation in C does not handle arguments correctly
[32026] strerror/strsignal TLS not handled correctly for secondary namespaces
[32052] Name space violation in fortify wrappers
Version 2.40

35
string/strerror_l.c
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@ -20,7 +20,7 @@
#include <stdio.h>
#include <string.h>
#include <tls-internal.h>
#include <libc-internal.h>
static const char *
translate (const char *str, locale_t loc)
@ -31,6 +31,12 @@ translate (const char *str, locale_t loc)
return res;
}
static char *
unknown_error (locale_t loc)
{
return (char *) translate ("Unknown error", loc);
}
/* Return a string describing the errno code in ERRNUM. */
char *
@ -40,18 +46,25 @@ __strerror_l (int errnum, locale_t loc)
char *err = (char *) __get_errlist (errnum);
if (__glibc_unlikely (err == NULL))
{
struct tls_internal_t *tls_internal = __glibc_tls_internal ();
free (tls_internal->strerror_l_buf);
if (__asprintf (&tls_internal->strerror_l_buf, "%s%d",
translate ("Unknown error ", loc), errnum) > 0)
err = tls_internal->strerror_l_buf;
else
if (__libc_initial)
{
/* The memory was freed above. */
tls_internal->strerror_l_buf = NULL;
/* Provide a fallback translation. */
err = (char *) translate ("Unknown error", loc);
struct tls_internal_t *tls_internal = __glibc_tls_internal ();
free (tls_internal->strerror_l_buf);
if (__asprintf (&tls_internal->strerror_l_buf, "%s%d",
translate ("Unknown error ", loc), errnum) > 0)
err = tls_internal->strerror_l_buf;
else
{
/* The memory was freed above. */
tls_internal->strerror_l_buf = NULL;
/* Provide a fallback translation. */
err = unknown_error (loc);
}
}
else
/* Secondary namespaces use a different malloc, so cannot
participate in the buffer management. */
err = unknown_error (loc);
}
else
err = (char *) translate (err, loc);

34
string/strsignal.c
View File

@ -21,6 +21,7 @@
#include <string.h>
#include <libintl.h>
#include <tls-internal.h>
#include <libc-internal.h>
/* Return a string describing the meaning of the signal number SIGNUM. */
char *
@ -30,21 +31,28 @@ strsignal (int signum)
if (desc != NULL)
return _(desc);
struct tls_internal_t *tls_internal = __glibc_tls_internal ();
free (tls_internal->strsignal_buf);
if (__libc_initial)
{
struct tls_internal_t *tls_internal = __glibc_tls_internal ();
free (tls_internal->strsignal_buf);
int r;
int r;
#ifdef SIGRTMIN
if (signum >= SIGRTMIN && signum <= SIGRTMAX)
r = __asprintf (&tls_internal->strsignal_buf, _("Real-time signal %d"),
signum - SIGRTMIN);
else
if (signum >= SIGRTMIN && signum <= SIGRTMAX)
r = __asprintf (&tls_internal->strsignal_buf, _("Real-time signal %d"),
signum - SIGRTMIN);
else
#endif
r = __asprintf (&tls_internal->strsignal_buf, _("Unknown signal %d"),
signum);
r = __asprintf (&tls_internal->strsignal_buf, _("Unknown signal %d"),
signum);
if (r == -1)
tls_internal->strsignal_buf = NULL;
return tls_internal->strsignal_buf;
if (r >= 0)
return tls_internal->strsignal_buf;
else
tls_internal->strsignal_buf = NULL;
}
/* Fall through on asprintf error, and for !__libc_initial:
secondary namespaces use a different malloc and cannot
participate in the buffer management. */
return _("Unknown signal");
}