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.