[LLVMbugs] [Bug 2734] New: write(buf) points to uninitialised bytes

bugzilla-daemon at cs.uiuc.edu bugzilla-daemon at cs.uiuc.edu
Sat Aug 30 09:17:01 PDT 2008


           Summary: write(buf) points to uninitialised bytes
           Product: tools
           Version: trunk
          Platform: PC
        OS/Version: Linux
            Status: NEW
          Severity: normal
          Priority: P2
         Component: llvm-gcc
        AssignedTo: unassignedbugs at nondot.org
        ReportedBy: nicholas at mxc.ca
                CC: llvmbugs at cs.uiuc.edu

This commandline:

llvm-gcc/install/libexec/gcc/i686-pc-linux-gnu/4.2.1/cc1 -quiet -iprefix
llvm/test/FrontendC/2007-05-08-PCH.c -quiet -dumpbase 2007-05-08-PCH.c
-mtune=generic -auxbase 2007-05-08-PCH -w -o /tmp/ccAMTp4m.s --output-pch=

triggers a valgrind notice:

==28075== Syscall param write(buf) points to uninitialised byte(s)
==28075==    at 0x7E24FCE: __write_nocancel (in /usr/lib/debug/libc-2.7.so)
==28075==    by 0x7DCF162: new_do_write (fileops.c:520)
==28075==    by 0x7DCF435: _IO_do_write@@GLIBC_2.1 (fileops.c:492)
==28075==    by 0x7DCFFDF: _IO_file_overflow@@GLIBC_2.1 (fileops.c:871)
==28075==    by 0x7DCF296: _IO_file_xsputn@@GLIBC_2.1 (fileops.c:1348)
==28075==    by 0x7DCE3C1: fwrite_unlocked (iofwrite_u.c:47)
==28075==    by 0x848E243: ggc_pch_write_object (in
==28075==  Address 0x800a186 is not stack'd, malloc'd or (recently) free'd

which doesn't have a particularly useful stacktrace in gdb either:

(gdb) bt
#0  0x07e24fce in __write_nocancel () from /usr/lib/debug/libc.so.6
#1  0x07dcf48f in _IO_new_file_write (f=0x96eabb0, data=0x800a000, n=4096)
    at fileops.c:1266
#2  0x07dcf163 in new_do_write (fp=0x96eabb0, 
    data=0x800a000 "__builtin_asinf", to_do=4096) at fileops.c:520
#3  0x07dcf436 in _IO_new_do_write (fp=0x96eabb0, 
    data=0x800a000 "__builtin_asinf", to_do=4096) at fileops.c:492
#4  0x07dcffe0 in _IO_new_file_overflow (f=0x96eabb0, ch=-1) at fileops.c:871
#5  0x07dcf297 in _IO_new_file_xsputn (f=0x96eabb0, data=0x96b7625, n=14)
    at fileops.c:1348
#6  0x07dce3c2 in *__GI_fwrite_unlocked (buf=0x96b7625, size=14, count=1, 
    fp=0x96eabb0) at iofwrite_u.c:47
#7  0x0848e244 in ggc_pch_write_object ()
#8  0x000007bc in ?? ()
#9  0x00005000 in ?? ()
#10 0x0984b630 in ?? ()
#11 0x096eabb0 in ?? ()
#12 0x00000001 in ?? ()
#13 0x0984b630 in ?? ()
#14 0x096eabb0 in ?? ()
#15 0x096b7625 in ?? ()
#16 0x00005000 in ?? ()

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