From 591732169550b26608f186c9927f4cf9a47d99d5 Mon Sep 17 00:00:00 2001 From: Tom Tromey Date: Mon, 17 May 2021 12:55:18 -0600 Subject: Fix ubsan build I tried a build using the undefined behavior sanitizer, and gcc gave this error: In file included from /usr/include/string.h:495, from ../gnulib/import/string.h:41, from ../../binutils-gdb/gdb/../gdbsupport/common-defs.h:95, from ../../binutils-gdb/gdb/nat/linux-osdata.c:20: In function 'char* strncpy(char*, const char*, size_t)', inlined from 'void time_from_time_t(char*, int, TIME_T)' at ../../binutils-gdb/gdb/nat/linux-osdata.c:923:15, inlined from 'void time_from_time_t(char*, int, TIME_T)' at ../../binutils-gdb/gdb/nat/linux-osdata.c:911:1, inlined from 'void linux_xfer_osdata_sem(buffer*)' at ../../binutils-gdb/gdb/nat/linux-osdata.c:1082:22: /usr/include/bits/string_fortified.h:106:34: error: 'char* __builtin_strncpy(char*, const char*, long unsigned int)' specified bound 32 equals destination size [-Werror=stringop-truncation] This patch fixes the problem by subtracting one from the length parameter to strncpy. I changed a couple of other similar functions -- gcc does not warn about these, but I didn't see any substantial difference between the different cases, and I think these are just latent warnings, to be triggered in the future by a change to inlining heuristics. gdb/ChangeLog 2021-05-17 Tom Tromey * nat/linux-osdata.c (user_from_uid, time_from_time_t) (group_from_gid): Subtract one from strncpy length. --- gdb/nat/linux-osdata.c | 6 +++--- 1 file changed, 3 insertions(+), 3 deletions(-) (limited to 'gdb/nat') diff --git a/gdb/nat/linux-osdata.c b/gdb/nat/linux-osdata.c index 7034dd8..12f66d3 100644 --- a/gdb/nat/linux-osdata.c +++ b/gdb/nat/linux-osdata.c @@ -212,7 +212,7 @@ user_from_uid (char *user, int maxlen, uid_t uid) if (pwentry) { - strncpy (user, pwentry->pw_name, maxlen); + strncpy (user, pwentry->pw_name, maxlen - 1); /* Ensure that the user name is null-terminated. */ user[maxlen - 1] = '\0'; } @@ -920,7 +920,7 @@ time_from_time_t (char *time, int maxlen, TIME_T seconds) characters long. */ char buf[30]; const char *time_str = ctime_r (&t, buf); - strncpy (time, time_str, maxlen); + strncpy (time, time_str, maxlen - 1); time[maxlen - 1] = '\0'; } } @@ -935,7 +935,7 @@ group_from_gid (char *group, int maxlen, gid_t gid) if (grentry) { - strncpy (group, grentry->gr_name, maxlen); + strncpy (group, grentry->gr_name, maxlen - 1); /* Ensure that the group name is null-terminated. */ group[maxlen - 1] = '\0'; } -- cgit v1.1