os/io.c: fix unitialised bytes

... by implementing some kind of recalloc (mix of realloc and calloc). Fixes this valgrind finding: ==7061== Syscall param writev(vector[...]) points to uninitialised byte(s) ==7061== at 0x781EFE0: __writev_nocancel (syscall-template.S:84) ==7061== by 0x488974: _XSERVTransSocketWritev (Xtranssock.c:2914) ==7061== by 0x47DBD3: FlushClient (io.c:1080) ==7061== by 0x47DBD3: FlushAllOutput.part.0 (io.c:817) ==7061== by 0x477304: WaitForSomething (WaitFor.c:246) ==7061== by 0x434369: Dispatch (NXdispatch.c:360) ==7061== by 0x40EB92: main (main.c:353) ==7061== Address 0x102106f3 is 50,211 bytes inside a block of size 54,308 alloc'd ==7061== at 0x4C2FD5F: realloc (in /usr/lib/valgrind/vgpreload_memcheck-amd64-linux.so) ==7061== by 0x47F08F: FlushClient (io.c:1123) ==7061== by 0x47F307: WriteToClient (io.c:991) ==7061== by 0x42903C: doListFontsAndAliases (NXdixfonts.c:660) ==7061== by 0x42B7D6: ListFonts (NXdixfonts.c:735) ==7061== by 0x433A6D: ProcListFonts (NXdispatch.c:989) ==7061== by 0x4344A5: Dispatch (NXdispatch.c:482) ==7061== by 0x40EB92: main (main.c:353) ==7061== Uninitialised value was created by a heap allocation ==7061== at 0x4C2FD5F: realloc (in /usr/lib/valgrind/vgpreload_memcheck-amd64-linux.so) ==7061== by 0x47F08F: FlushClient (io.c:1123) ==7061== by 0x47F307: WriteToClient (io.c:991) ==7061== by 0x42903C: doListFontsAndAliases (NXdixfonts.c:660) ==7061== by 0x42B7D6: ListFonts (NXdixfonts.c:735) ==7061== by 0x433A6D: ProcListFonts (NXdispatch.c:989) ==7061== by 0x4344A5: Dispatch (NXdispatch.c:482) ==7061== by 0x40EB92: main (main.c:353) ==7061==

os/io.c: fix unitialised bytes
e5975a70 · Ulrich Sibiller · Mike Gabriel · 389e3a44 · e5975a70
Commit e5975a70 authored Jun 21, 2018 by Ulrich Sibiller Committed by Mike Gabriel Jul 03, 2018
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io.c nx-X11/programs/Xserver/os/io.c +6 -1

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--- a/nx-X11/programs/Xserver/os/io.c
+++ b/nx-X11/programs/Xserver/os/io.c
@@ -1120,7 +1120,12 @@ FlushClient(ClientPtr who, OsCommPtr oc, const void *__extraBuf, int extraCount)
 		unsigned char *obuf = NULL;
 		if (notWritten + BUFSIZE <= INT_MAX) {
-		    obuf = realloc(oco->buf, notWritten + BUFSIZE);
+		    obuf = calloc(1, notWritten + BUFSIZE);
+		    if (obuf)
+		    {
+			memmove(obuf, oco->buf, oco->size);
+			free(oco->buf);
+		    }
 		}
 		if (!obuf)
 		{