[Bug c/57862] New: invalid read struct uint32_t member (ARMV5)

["mendola at gmail dot com" <gcc-bugzilla@gcc.gnu.org>]

http://gcc.gnu.org/bugzilla/show_bug.cgi?id=57862

            Bug ID: 57862
           Summary: invalid read struct uint32_t member (ARMV5)
           Product: gcc
           Version: 4.7.2
            Status: UNCONFIRMED
          Severity: critical
          Priority: P3
         Component: c
          Assignee: unassigned at gcc dot gnu.org
          Reporter: mendola at gmail dot com

Created attachment 30481
  --> http://gcc.gnu.org/bugzilla/attachment.cgi?id=30481&action=edit
The preprocessed file

# uname -a
Linux tqma28 2.6.35.3 #1 PREEMPT Sun Sep 11 17:38:39 CEST 2011 armv5tejl
GNU/Linux

# gcc-4.7 -v -save-temps main.c -march=armv5t
Using built-in specs.
COLLECT_GCC=gcc-4.7
COLLECT_LTO_WRAPPER=/usr/lib/gcc/arm-linux-gnueabi/4.7/lto-wrapper
Target: arm-linux-gnueabi
Configured with: ../src/configure -v --with-pkgversion='Debian 4.7.2-5'
--with-bugurl=file:///usr/share/doc/gcc-4.7/README.Bugs
--enable-languages=c,c++,go,fortran,objc,obj-c++ --prefix=/usr
--program-suffix=-4.7 --enable-shared --enable-linker-build-id
--with-system-zlib --libexecdir=/usr/lib --without-included-gettext
--enable-threads=posix --with-gxx-include-dir=/usr/include/c++/4.7
--libdir=/usr/lib --enable-nls --with-sysroot=/ --enable-clocale=gnu
--enable-libstdcxx-debug --enable-libstdcxx-time=yes --enable-gnu-unique-object
--disable-libitm --enable-plugin --enable-objc-gc --disable-sjlj-exceptions
--with-arch=armv4t --with-float=soft --enable-checking=release
--build=arm-linux-gnueabi --host=arm-linux-gnueabi --target=arm-linux-gnueabi
Thread model: posix
gcc version 4.7.2 (Debian 4.7.2-5) 
COLLECT_GCC_OPTIONS='-v' '-save-temps' '-march=armv5t' '-mfloat-abi=soft'
'-mtls-dialect=gnu'
 /usr/lib/gcc/arm-linux-gnueabi/4.7/cc1 -E -quiet -v -imultilib . -imultiarch
arm-linux-gnueabi main.c -march=armv5t -mfloat-abi=soft -mtls-dialect=gnu
-fpch-preprocess -o main.i
ignoring nonexistent directory "/usr/local/include/arm-linux-gnueabi"
ignoring nonexistent directory
"/usr/lib/gcc/arm-linux-gnueabi/4.7/../../../../arm-linux-gnueabi/include"
#include "..." search starts here:
#include <...> search starts here:
 /usr/lib/gcc/arm-linux-gnueabi/4.7/include
 /usr/local/include
 /usr/lib/gcc/arm-linux-gnueabi/4.7/include-fixed
 /usr/include/arm-linux-gnueabi
 /usr/include
End of search list.
COLLECT_GCC_OPTIONS='-v' '-save-temps' '-march=armv5t' '-mfloat-abi=soft'
'-mtls-dialect=gnu'
 /usr/lib/gcc/arm-linux-gnueabi/4.7/cc1 -fpreprocessed main.i -quiet -dumpbase
main.c -march=armv5t -mfloat-abi=soft -mtls-dialect=gnu -auxbase main -version
-o main.s
GNU C (Debian 4.7.2-5) version 4.7.2 (arm-linux-gnueabi)
        compiled by GNU C version 4.7.2, GMP version 5.0.5, MPFR version
3.1.0-p10, MPC version 0.9
GGC heuristics: --param ggc-min-expand=38 --param ggc-min-heapsize=15631
GNU C (Debian 4.7.2-5) version 4.7.2 (arm-linux-gnueabi)
        compiled by GNU C version 4.7.2, GMP version 5.0.5, MPFR version
3.1.0-p10, MPC version 0.9
GGC heuristics: --param ggc-min-expand=38 --param ggc-min-heapsize=15631
Compiler executable checksum: da7c3c2f0b4be4af23076cf3c1dfbf58
COLLECT_GCC_OPTIONS='-v' '-save-temps' '-march=armv5t' '-mfloat-abi=soft'
'-mtls-dialect=gnu'
 as -v -march=armv5t -mfloat-abi=soft -meabi=5 -o main.o main.s
GNU assembler version 2.22 (arm-linux-gnueabi) using BFD version (GNU Binutils
for Debian) 2.22
COMPILER_PATH=/usr/lib/gcc/arm-linux-gnueabi/4.7/:/usr/lib/gcc/arm-linux-gnueabi/4.7/:/usr/lib/gcc/arm-linux-gnueabi/:/usr/lib/gcc/arm-linux-gnueabi/4.7/:/usr/lib/gcc/arm-linux-gnueabi/
LIBRARY_PATH=/usr/lib/gcc/arm-linux-gnueabi/4.7/:/usr/lib/gcc/arm-linux-gnueabi/4.7/../../../arm-linux-gnueabi/:/usr/lib/gcc/arm-linux-gnueabi/4.7/../../../:/lib/arm-linux-gnueabi/:/lib/:/usr/lib/arm-linux-gnueabi/:/usr/lib/
COLLECT_GCC_OPTIONS='-v' '-save-temps' '-march=armv5t' '-mfloat-abi=soft'
'-mtls-dialect=gnu'
 /usr/lib/gcc/arm-linux-gnueabi/4.7/collect2 --sysroot=/ --build-id
--no-add-needed --eh-frame-hdr -dynamic-linker /lib/ld-linux.so.3 -X
--hash-style=both -m armelf_linux_eabi
/usr/lib/gcc/arm-linux-gnueabi/4.7/../../../arm-linux-gnueabi/crt1.o
/usr/lib/gcc/arm-linux-gnueabi/4.7/../../../arm-linux-gnueabi/crti.o
/usr/lib/gcc/arm-linux-gnueabi/4.7/crtbegin.o
-L/usr/lib/gcc/arm-linux-gnueabi/4.7
-L/usr/lib/gcc/arm-linux-gnueabi/4.7/../../../arm-linux-gnueabi
-L/usr/lib/gcc/arm-linux-gnueabi/4.7/../../.. -L/lib/arm-linux-gnueabi
-L/usr/lib/arm-linux-gnueabi main.o -lgcc --as-needed -lgcc_s --no-as-needed
-lc -lgcc --as-needed -lgcc_s --no-as-needed
/usr/lib/gcc/arm-linux-gnueabi/4.7/crtend.o
/usr/lib/gcc/arm-linux-gnueabi/4.7/../../../arm-linux-gnueabi/crtn.o


This is the following output executing it:

# ./a.out 
myInAddr.s_addr: 513
theIpHeader->daddr: 513
1.2.3.4
1.2.0.0

and that 1.2.0.0 should be 1.2.3.4. The same code works fine on ARMV7
architectures or x86

I believe that the culprit is in the assignment:

myInAddr.s_addr = theIpHeader->daddr;

note that replacing that assignment with:

memcpy(&myInAddr.s_addr, &(theIpHeader->daddr), sizeof(theIpHeader->daddr));

nothing changes, while using gcc 4.4 I get:

# ./a.out 
myInAddr.s_addr: 67305985
theIpHeader->daddr: 513
1.2.3.4
1.2.3.4

note now the bytes behind the memory are corrected reported as 1.2.3.4 but
printing the fields ad integer they report a wrong value.