From b0d3f7858c659a0a275c8ba1c1879cd53f2bd25e Mon Sep 17 00:00:00 2001 From: Florian Weimer Date: Tue, 19 May 2020 14:09:38 +0200 Subject: [PATCH] nss_compat: internal_end*ent may clobber errno, hiding ERANGE [BZ #25976] During cleanup, before returning from get*_r functions, the end*ent calls must not change errno. Otherwise, an ERANGE error from the underlying implementation can be hidden, causing unexpected lookup failures. This commit introduces an internal_end*ent_noerror function which saves and restore errno, and marks the original internal_end*ent function as warn_unused_result, so that it is used only in contexts were errors from it can be handled explicitly. Reviewed-by: DJ Delorie (cherry picked from commit 790b8dda4455865cb8c3a47801f4304c1a43baf6) --- NEWS | 1 + nss/nss_compat/compat-grp.c | 15 ++++++++++++--- nss/nss_compat/compat-initgroups.c | 13 +++++++++++-- nss/nss_compat/compat-pwd.c | 15 ++++++++++++--- nss/nss_compat/compat-spwd.c | 14 +++++++++++--- 5 files changed, 47 insertions(+), 11 deletions(-) diff --git a/NEWS b/NEWS index 2df50c1da4..7cfd073248 100644 --- a/NEWS +++ b/NEWS @@ -39,6 +39,7 @@ The following bugs are resolved with this release: [25204] Ignore LD_PREFER_MAP_32BIT_EXEC for SUID programs [25225] ld.so fails to link on x86 if GCC defaults to -fcf-protection [25232] No const correctness for strchr et al. for Clang++ + [25976] nss_compat: internal_end*ent may clobber errno, hiding ERANGE Security related changes: diff --git a/nss/nss_compat/compat-grp.c b/nss/nss_compat/compat-grp.c index 8ee0799a56..ad7da65c28 100644 --- a/nss/nss_compat/compat-grp.c +++ b/nss/nss_compat/compat-grp.c @@ -142,7 +142,7 @@ _nss_compat_setgrent (int stayopen) } -static enum nss_status +static enum nss_status __attribute_warn_unused_result__ internal_endgrent (ent_t *ent) { if (ent->stream != NULL) @@ -163,6 +163,15 @@ internal_endgrent (ent_t *ent) return NSS_STATUS_SUCCESS; } +/* Like internal_endgrent, but preserve errno in all cases. */ +static void +internal_endgrent_noerror (ent_t *ent) +{ + int saved_errno = errno; + enum nss_status unused __attribute__ ((unused)) = internal_endgrent (ent); + __set_errno (saved_errno); +} + enum nss_status _nss_compat_endgrent (void) { @@ -483,7 +492,7 @@ _nss_compat_getgrnam_r (const char *name, struct group *grp, if (result == NSS_STATUS_SUCCESS) result = internal_getgrnam_r (name, grp, &ent, buffer, buflen, errnop); - internal_endgrent (&ent); + internal_endgrent_noerror (&ent); return result; } @@ -612,7 +621,7 @@ _nss_compat_getgrgid_r (gid_t gid, struct group *grp, if (result == NSS_STATUS_SUCCESS) result = internal_getgrgid_r (gid, grp, &ent, buffer, buflen, errnop); - internal_endgrent (&ent); + internal_endgrent_noerror (&ent); return result; } diff --git a/nss/nss_compat/compat-initgroups.c b/nss/nss_compat/compat-initgroups.c index 52b9ce2b99..6d016d6f68 100644 --- a/nss/nss_compat/compat-initgroups.c +++ b/nss/nss_compat/compat-initgroups.c @@ -133,7 +133,7 @@ internal_setgrent (ent_t *ent) } -static enum nss_status +static enum nss_status __attribute_warn_unused_result__ internal_endgrent (ent_t *ent) { if (ent->stream != NULL) @@ -157,6 +157,15 @@ internal_endgrent (ent_t *ent) return NSS_STATUS_SUCCESS; } +/* Like internal_endgrent, but preserve errno in all cases. */ +static void +internal_endgrent_noerror (ent_t *ent) +{ + int saved_errno = errno; + enum nss_status unused __attribute__ ((unused)) = internal_endgrent (ent); + __set_errno (saved_errno); +} + /* Add new group record. */ static void add_group (long int *start, long int *size, gid_t **groupsp, long int limit, @@ -501,7 +510,7 @@ _nss_compat_initgroups_dyn (const char *user, gid_t group, long int *start, done: scratch_buffer_free (&tmpbuf); - internal_endgrent (&intern); + internal_endgrent_noerror (&intern); return status; } diff --git a/nss/nss_compat/compat-pwd.c b/nss/nss_compat/compat-pwd.c index 2a39fd08b7..23e329f111 100644 --- a/nss/nss_compat/compat-pwd.c +++ b/nss/nss_compat/compat-pwd.c @@ -259,7 +259,7 @@ _nss_compat_setpwent (int stayopen) } -static enum nss_status +static enum nss_status __attribute_warn_unused_result__ internal_endpwent (ent_t *ent) { if (ent->stream != NULL) @@ -287,6 +287,15 @@ internal_endpwent (ent_t *ent) return NSS_STATUS_SUCCESS; } +/* Like internal_endpwent, but preserve errno in all cases. */ +static void +internal_endpwent_noerror (ent_t *ent) +{ + int saved_errno = errno; + enum nss_status unused __attribute__ ((unused)) = internal_endpwent (ent); + __set_errno (saved_errno); +} + enum nss_status _nss_compat_endpwent (void) { @@ -822,7 +831,7 @@ _nss_compat_getpwnam_r (const char *name, struct passwd *pwd, if (result == NSS_STATUS_SUCCESS) result = internal_getpwnam_r (name, pwd, &ent, buffer, buflen, errnop); - internal_endpwent (&ent); + internal_endpwent_noerror (&ent); return result; } @@ -1061,7 +1070,7 @@ _nss_compat_getpwuid_r (uid_t uid, struct passwd *pwd, if (result == NSS_STATUS_SUCCESS) result = internal_getpwuid_r (uid, pwd, &ent, buffer, buflen, errnop); - internal_endpwent (&ent); + internal_endpwent_noerror (&ent); return result; } diff --git a/nss/nss_compat/compat-spwd.c b/nss/nss_compat/compat-spwd.c index 4e4980fd78..3f1fde91f9 100644 --- a/nss/nss_compat/compat-spwd.c +++ b/nss/nss_compat/compat-spwd.c @@ -215,7 +215,7 @@ _nss_compat_setspent (int stayopen) } -static enum nss_status +static enum nss_status __attribute_warn_unused_result__ internal_endspent (ent_t *ent) { if (ent->stream != NULL) @@ -244,6 +244,15 @@ internal_endspent (ent_t *ent) return NSS_STATUS_SUCCESS; } +/* Like internal_endspent, but preserve errno in all cases. */ +static void +internal_endspent_noerror (ent_t *ent) +{ + int saved_errno = errno; + enum nss_status unused __attribute__ ((unused)) = internal_endspent (ent); + __set_errno (saved_errno); +} + enum nss_status _nss_compat_endspent (void) { @@ -261,7 +270,6 @@ _nss_compat_endspent (void) return result; } - static enum nss_status getspent_next_nss_netgr (const char *name, struct spwd *result, ent_t *ent, char *group, char *buffer, size_t buflen, @@ -786,7 +794,7 @@ _nss_compat_getspnam_r (const char *name, struct spwd *pwd, if (result == NSS_STATUS_SUCCESS) result = internal_getspnam_r (name, pwd, &ent, buffer, buflen, errnop); - internal_endspent (&ent); + internal_endspent_noerror (&ent); return result; }