FS#3980 - umbim "address-of-packed-member" compilation warning/errors

[openwrt-bot]

rektide:

Environment: arm ipq806x / netgear r7800, trunk
GCC: 10.x

Trying to compile umbim results in a warning/erorr:

make[3]: Entering directory '/usr/local/src/openwrt/package/network/utils/umbim' mkdir -p /usr/local/src/openwrt/dl SHELL= flock /usr/local/src/openwrt/tmp/.umbim-2019-09-11-184b707d.tar.xz.flock -c ' /usr/local/src/openwrt/scripts/download.pl "/usr/local/src/openwrt/dl" "umbim-201 9-09-11-184b707d.tar.xz" "482ff69144f81fafed99035840f5a24e772472f2df2f3ac0219d6de791ac5835" "" || ( echo "Checking out files from the git repository..."; mkdir -p /us r/local/src/openwrt/tmp/dl && cd /usr/local/src/openwrt/tmp/dl && rm -rf umbim-2019-09-11-184b707d && [ \! -d umbim-2019-09-11-184b707d ] && git clone https://git.openw rt.org/project/umbim.git umbim-2019-09-11-184b707d && (cd umbim-2019-09-11-184b707d && git checkout 184b707ddaa0acee84d02e0ffe599cb8b67782bd && git submodule update --in it --recursive) && echo "Packing checkout..." && export TAR_TIMESTAMP=`cd umbim-2019-09-11-184b707d && git log -1 --format='\''@%ct'\''` && rm -rf umbim-2019-09-11-184b7 07d/.git && tar --numeric-owner --owner=0 --group=0 --mode=a-s --sort=name ${TAR_TIMESTAMP:+--mtime="$TAR_TIMESTAMP"} -c umbim-2019-09-11-184b707d | xz -zc -7e > /usr/local/src/openwrt/tmp/dl/umbim-2019-09-11-184b707d.tar.xz && mv /usr/local/src/openwrt/tmp/dl/umbim-2019-09-11-184b707d.tar.xz /usr/local/src/openwrt/dl/ && rm -rf umbim-2019-09-11-184b707d; ) ' touch /usr/local/src/openwrt/build_dir/target-arm_cortex-a15+neon-vfpv4_musl_eabi/umbim-2019-09-11-184b707d/.prepared_d06039bd652ab99df8802435f3362dc7_6664517399ebbbc92a 37c5bb081b5c53_check . /usr/local/src/openwrt/include/shell.sh; xzcat /usr/local/src/openwrt/dl/umbim-2019-09-11-184b707d.tar.xz | tar -C /usr/local/src/openwrt/build_dir/target-arm_cortex-a 15+neon-vfpv4_musl_eabi/umbim-2019-09-11-184b707d/.. -xf - [ ! -d ./src/ ] || cp -fpR ./src/. /usr/local/src/openwrt/build_dir/target-arm_cortex-a15+neon-vfpv4_musl_eabi/umbim-2019-09-11-184b707d touch /usr/local/src/openwrt/build_dir/target-arm_cortex-a15+neon-vfpv4_musl_eabi/umbim-2019-09-11-184b707d/.prepared_d06039bd652ab99df8802435f3362dc7_6664517399ebbbc92a 37c5bb081b5c53 rm -f /usr/local/src/openwrt/build_dir/target-arm_cortex-a15+neon-vfpv4_musl_eabi/umbim-2019-09-11-184b707d/.configured_* rm -f /usr/local/src/openwrt/staging_dir/target-arm_cortex-a15+neon-vfpv4_musl_eabi/stamp/.umbim_installed mkdir -p /usr/local/src/openwrt/build_dir/target-arm_cortex-a15+neon-vfpv4_musl_eabi/umbim-2019-09-11-184b707d (cd /usr/local/src/openwrt/build_dir/target-arm_cortex-a15+neon-vfpv4_musl_eabi/umbim-2019-09-11-184b707d; CFLAGS="-Os -pipe -fno-caller-saves -fno-plt -fhonour-copts -W [1/5] Building C object CMakeFiles/umbim.dir/cli.c.o FAILED: CMakeFiles/umbim.dir/cli.c.o /usr/local/src/openwrt/staging_dir/toolchain-arm_cortex-a15+neon-vfpv4_gcc-10.3.0_musl_eabi/bin/arm-openwrt-linux-muslgnueabi-gcc -Os -pipe -fno-caller-saves -fno-plt -fhonour-copts -Wno-error=unused-but-set-va riable -Wno-error=unused-result -mfloat-abi=hard -fmacro-prefix-map=/usr/local/src/openwrt/build_dir/target-arm_cortex-a15+neon-vfpv4_musl_eabi/umbim-2019-09-11-184b707d=umbim-2019-09-11-184b707d -Wformat -Werror =format-security -fstack-protector -D_FORTIFY_SOURCE=1 -Wl,-z,now -Wl,-z,relro -I/usr/local/src/openwrt/staging_dir/target-arm_cortex-a15+neon-vfpv4_musl_eabi/usr/include -ffunction-sections -fdata-sections -DNDE BUG -Os -ggdb -Wextra -Wall -Werror --std=gnu99 -Wmissing-declarations -Wno-unused-parameter -MD -MT CMakeFiles/umbim.dir/cli.c.o -MF CMakeFiles/umbim.dir/cli.c.o.d -o CMakeFiles/umbim.dir/cli.c.o -c cli.c cli.c: In function 'mbim_device_caps_response': cli.c:55:29: error: taking address of packed member of 'struct mbim_basic_connect_device_caps_r' may result in an unaligned pointer value [-Werror=address-of-packed-member] 55 | deviceid = mbim_get_string(&caps->deviceid, buffer); | ^~~~~~~~~~~~~~~ cli.c:56:33: error: taking address of packed member of 'struct mbim_basic_connect_device_caps_r' may result in an unaligned pointer value [-Werror=address-of-packed-member] 56 | firmwareinfo = mbim_get_string(&caps->firmwareinfo, buffer); | ^~~~~~~~~~~~~~~~~~~ cli.c:57:33: error: taking address of packed member of 'struct mbim_basic_connect_device_caps_r' may result in an unaligned pointer value [-Werror=address-of-packed-member] 57 | hardwareinfo = mbim_get_string(&caps->hardwareinfo, buffer); | ^~~~~~~~~~~~~~~~~~~ cli.c: In function 'mbim_home_provider_response': cli.c:111:32: error: taking address of packed member of 'struct mbimprovider' may result in an unaligned pointer value [-Werror=address-of-packed-member] 111 | provider_id = mbim_get_string(&provider->providerid, buffer); | ^~~~~~~~~~~~~~~~~~~~~ cli.c:112:34: error: taking address of packed member of 'struct mbimprovider' may result in an unaligned pointer value [-Werror=address-of-packed-member] 112 | provider_name = mbim_get_string(&provider->providername, buffer); | ^~~~~~~~~~~~~~~~~~~~~~~ cli.c: In function 'mbim_registration_response': cli.c:135:32: error: taking address of packed member of 'struct mbim_basic_connect_register_state_r' may result in an unaligned pointer value [-Werror=address-of-packed-member] 135 | provider_id = mbim_get_string(&state->providerid, buffer); | ^~~~~~~~~~~~~~~~~~ cli.c:136:34: error: taking address of packed member of 'struct mbim_basic_connect_register_state_r' may result in an unaligned pointer value [-Werror=address-of-packed-member] 136 | provider_name = mbim_get_string(&state->providername, buffer); | ^~~~~~~~~~~~~~~~~~~~ cli.c:137:32: error: taking address of packed member of 'struct mbim_basic_connect_register_state_r' may result in an unaligned pointer value [-Werror=address-of-packed-member] 137 | roamingtext = mbim_get_string(&state->roamingtext, buffer); | ^~~~~~~~~~~~~~~~~~~ cli.c: In function 'mbim_subscriber_response': cli.c:171:33: error: taking address of packed member of 'struct mbim_basic_connect_subscriber_ready_status_r' may result in an unaligned pointer value [-Werror=address-of-packed-member]

[openwrt-bot]

stintel:

Please test https://git.openwrt.org/?p=openwrt/staging/stintel.git;a=commit;h=72f3dd38637ba89ee1fc4aabc877fee622fe9406

[openwrt-bot]

ldir:

Taking the address (pointer to) a member of a structure is unpredictable. There is no guarantee that the type of objects defined in the structure meet architecture alignment rules. ie. there's no guarantee that the 2 signed ints (32 bit) in the string structure are suitably aligned in memory for native cpu access which may require them at 2 or even 4 byte boundaries.

The truly horrible workaround is to pass pointers to a local version of the 'string' structure which is guaranteed to be suitably aligned by the compiler and then copy in/out to final destination in memory.

A suitable patch attached, which compiles for me but is in no way run-time tested.