Bug#871538: Makes apparmor FTBFS on mips64el (generated code thinks that 1 > 1)
Package: gcc-7
Version: 7.1.0-12
Severity: important
X-Debbugs-Cc: Tyler Hicks <tyhicks@canonical.com>, Seth Arnold <seth.arnold@canonical.com>
Hi!
we've debugged a FTBFS of src:apparmor on mips64el today together with
our Ubuntu friends on #apparmor, and we concluded it's probably a bug
somewhere in the toolchain rather than in src:apparmor:
Build logs:
https://buildd.debian.org/status/fetch.php?pkg=apparmor&arch=mips64el&ver=2.11.0-9&stamp=1502149450&raw=0
Reproduced on eller.debian.org.
We're discussing this upstream there:
https://bugs.launchpad.net/debian/+source/apparmor/+bug/1709360
Given the failure appeared after uploads/rebuilds with no source
change (only AppArmor profiles were modified), it looks very much like
it's caused by a change in the toolchain: gcc-7, perhaps?
"Interestingly", applying a patch that merely adds debugging output
(https://bugs.launchpad.net/debian/+source/apparmor/+bug/1709360/+attachment/4928923/+files/debug.patch)
makes the bug disappear.
The following gdb session seems to indicate that there's a toolchain
bug. According to Tyler Hicks <tyhicks@ubuntu.com>:
* aa_policy_cache_new() is called with max_caches equal to 1
* max_caches is not modified in aa_policy_cache_new()
* yet somehow (max_caches > 1) evaluates to true
eller% gdb --args ./apparmor_parser --base /tmp/aa-caching-7m80k_gp --skip-kernel-load -M tst/features_files/features.all --cache-loc /tmp/aa-caching-7m80k_gp/aa-alt-cachedf_u_391 -q --write-cache -r /tmp/aa-caching-7m80k_gp/sbin.pingy
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Reading symbols from ./apparmor_parser...done.
(gdb) break aa_policy_cache_new
Breakpoint 1 at 0x96f70: file policy_cache.c, line 135.
(gdb) run
Starting program: /home/intrigeri/apparmor-2.11.0/parser/apparmor_parser --base /tmp/aa-caching-7m80k_gp --skip-kernel-load -M tst/features_files/features.all --cache-loc /tmp/aa-caching-7m80k_gp/aa-alt-cachedf_u_391 -q --write-cache -r /tmp/aa-caching-7m80k_gp/sbin.pingy
[...]
Breakpoint 1, aa_policy_cache_new (policy_cache=0xffffffe7d8, kernel_features=0xaaaaca22a0, dirfd=-100, path=0xaaaaca42b0 "/tmp/aa-caching-7m80k_gp/aa-alt-cachedf_u_391",
max_caches=1) at policy_cache.c:135
135 return true;
(gdb) s
141 int setup_cache_tmp(const char **cachetmpname, const char *cachename)
(gdb) s
146 *cachetmpname = NULL;
(gdb) s
147 if (write_cache) {
(gdb) s
148 /* Otherwise, set up to save a cached copy */
(gdb) s
(gdb) s
main (argc=<optimized out>, argv=0xffffffea78) at parser_main.c:1124
1124 if (retval) {
(gdb)
1125 if (errno != ENOENT && errno != EEXIST) {
(gdb) s
1126 PERROR(_("Failed setting up policy cache (%s): %s\n"),
(gdb)
fprintf (__fmt=0xaaaac1aaa0 "Failed setting up policy cache (%s): %s\n", __stream=0xfff7eb24e8 <_IO_2_1_stderr_>) at /usr/include/mips64el-linux-gnuabi64/bits/stdio2.h:98
98 __va_arg_pack ());
(gdb)
Failed setting up policy cache (/tmp/aa-caching-7m80k_gp/aa-alt-cachedf_u_391): Operation not supported
main (argc=<optimized out>, argv=<optimized out>) at parser_main.c:1128
1128 return 1;
(gdb)
1199 }
(gdb)
0x000000fff7d386fc in __libc_start_main () from /lib/mips64el-linux-gnuabi64/libc.so.6
(gdb)
Single stepping until exit from function __libc_start_main,
which has no line number information.
[Inferior 1 (process 609) exited with code 01]
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