[Pkg-pascal-devel] Bug#888782: fp-compiler-3.0.4: fpselect segfaults on arm64

[peter green]

Tags 888782 +patch
Thanks

Freepascal upstream noted that this bug was not present in trunk, but didn't research when/how it was fixed, so I decided to do some digging in the source.

It turns out that the "generic syscalls" implementation of fpSelect (used for aarch64) translates the timeout parameter from a timeval (seconds and microseconds) to a timespec (seconds and nanoseconds) before passing it to the "pselect6" system call.

Unfortunately the version of the code in Debian 3.0.4 fails to check if the timeout is nil, dereferences the nil pointer and segfaults.

Using the "blame" tool on an unofficial github mirror of the freepascal source found the commit fixing the issue.

https://github.com/graemeg/freepascal/commit/e8335a145bfe3af52eed8d0d74ae3a461bbe9d1e

I turned the commit into a quilt patch, added it to the quilt series, built the compiler and was able to confirm it fixed the issue.

Debdiff is attatched, if noone else gets round to it first I'll probably commit and upload within the next week or so.

-------------- next part --------------
diff -Nru fpc-3.0.4+dfsg/debian/changelog fpc-3.0.4+dfsg/debian/changelog
--- fpc-3.0.4+dfsg/debian/changelog	2019-01-16 09:14:10.000000000 +0000
+++ fpc-3.0.4+dfsg/debian/changelog	2019-01-24 23:27:02.000000000 +0000
@@ -1,3 +1,10 @@
+fpc (3.0.4+dfsg-22) UNRELEASED; urgency=medium
+
+  * debian/patches/arm64-select.patch
+    - Fix fpSelect with nil timestamp on aarch64 (closes: 888782)
+
+ -- Peter Michael Green <plugwash at debian.org>  Thu, 24 Jan 2019 23:27:02 +0000
+
 fpc (3.0.4+dfsg-21) unstable; urgency=medium
 
   [ Paul Gevers ]
diff -Nru fpc-3.0.4+dfsg/debian/patches/arm64-select.patch fpc-3.0.4+dfsg/debian/patches/arm64-select.patch
--- fpc-3.0.4+dfsg/debian/patches/arm64-select.patch	1970-01-01 00:00:00.000000000 +0000
+++ fpc-3.0.4+dfsg/debian/patches/arm64-select.patch	2019-01-24 23:26:42.000000000 +0000
@@ -0,0 +1,37 @@
+This patch is based on the commit detailed below with paths adjusted
+to match the Debian fpc package --plugwash
+commit e8335a145bfe3af52eed8d0d74ae3a461bbe9d1e
+Author: Marco van de Voort <marcov at stack.nl>
+Date:   Wed Mar 30 19:21:05 2016 +0000
+
+     * fix timespec=nil for -dgeneric_linux_syscalls (aarch64) case.
+    
+    
+    git-svn-id: http://svn.freepascal.org/svn/fpc/trunk@33392 3ad0048d-3df7-0310-abae-a5850022a9f2
+
+diff --git a/rtl/linux/bunxsysc.inc b/rtl/linux/bunxsysc.inc
+index c8d7849672..c6d18be4e9 100644
+--- a/fpcsrc/rtl/linux/bunxsysc.inc
++++ b/fpcsrc/rtl/linux/bunxsysc.inc
+@@ -463,12 +463,18 @@ Function fpSelect(N:cint;readfds,writefds,exceptfds:pfdSet;TimeOut:PTimeVal):cin
+ {$if defined(generic_linux_syscalls)}
+ 
+ var ts : timespec;
++    pts : PTimeSpec;
+ begin
+-  ts.tv_sec := timeout^.tv_sec;
+-  ts.tv_nsec := timeout^.tv_usec * 1000;
++  pts:=nil;
++  if assigned(timeout) then
++    begin
++      pts:=@ts;
++      ts.tv_sec := timeout^.tv_sec;
++      ts.tv_nsec := timeout^.tv_usec * 1000;
++    end;
+   fpSelect:=do_syscall(syscall_nr_pselect6,n,
+                        tsysparam(readfds),tsysparam(writefds),
+-                       tsysparam(exceptfds),tsysparam(@ts),0);
++                       tsysparam(exceptfds),tsysparam(pts),0);
+ end;
+ 
+ {$else}
diff -Nru fpc-3.0.4+dfsg/debian/patches/series fpc-3.0.4+dfsg/debian/patches/series
--- fpc-3.0.4+dfsg/debian/patches/series	2019-01-16 08:33:37.000000000 +0000
+++ fpc-3.0.4+dfsg/debian/patches/series	2019-01-24 23:26:55.000000000 +0000
@@ -34,3 +34,4 @@
 fpcmake-m68k.patch
 ncurses6.patch
 fpc-r38400.patch
+arm64-select.patch