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author | Michael Catanzaro <mcatanzaro@redhat.com> | 2021-09-08 13:42:16 -0500 |
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committer | Michael Catanzaro <mcatanzaro@redhat.com> | 2021-09-08 16:19:28 -0500 |
commit | 92b264676ccd79c89da270aabc1ec466fa18cd0d (patch) | |
tree | b58f3ae632a362d51b38088648d4f208ec97cfe6 /src/nss-systemd | |
parent | 9f6ef467818f902fe5369c8e37a39a3901bdcf4f (diff) | |
download | systemd-92b264676ccd79c89da270aabc1ec466fa18cd0d.tar.gz |
nss-systemd: pack pw_passwd result into supplied buffer
getpwnam_r() guarantees that the strings in the struct passwd that it
returns are pointers into the buffer allocated by the application and
passed to getpwnam_r(). This means applications may choose to modify the
strings in place, as long as the length of the strings is not increased.
So it's wrong for us to return a static string here, we really do have
to copy it into the application-provided buffer like we do for all the
other strings.
This is only a theoretical problem since it would be very weird for an
application to modify the pw_passwd field, but I spotted this when
investigating a similar crash caused by glib editing a different field.
See also:
https://gitlab.gnome.org/GNOME/glib/-/merge_requests/2244
Diffstat (limited to 'src/nss-systemd')
-rw-r--r-- | src/nss-systemd/userdb-glue.c | 6 |
1 files changed, 4 insertions, 2 deletions
diff --git a/src/nss-systemd/userdb-glue.c b/src/nss-systemd/userdb-glue.c index a55790f641..c865ff0d82 100644 --- a/src/nss-systemd/userdb-glue.c +++ b/src/nss-systemd/userdb-glue.c @@ -35,6 +35,8 @@ int nss_pack_user_record( assert(hr->user_name); required = strlen(hr->user_name) + 1; + required += 2; /* strlen(PASSWORD_SEE_SHADOW) + 1 */ + assert_se(rn = user_record_real_name(hr)); required += strlen(rn) + 1; @@ -51,12 +53,12 @@ int nss_pack_user_record( .pw_name = buffer, .pw_uid = hr->uid, .pw_gid = user_record_gid(hr), - .pw_passwd = (char*) PASSWORD_SEE_SHADOW, }; assert(buffer); - pwd->pw_gecos = stpcpy(pwd->pw_name, hr->user_name) + 1; + pwd->pw_passwd = stpcpy(pwd->pw_name, hr->user_name) + 1; + pwd->pw_gecos = stpcpy(pwd->pw_passwd, PASSWORD_SEE_SHADOW) + 1; pwd->pw_dir = stpcpy(pwd->pw_gecos, rn) + 1; pwd->pw_shell = stpcpy(pwd->pw_dir, hd) + 1; strcpy(pwd->pw_shell, shell); |