# git rev-parse -q --verify 3c8ba0d61d04ced9f8d9ff93977995a9e4e96e91^{commit} 3c8ba0d61d04ced9f8d9ff93977995a9e4e96e91 already have revision, skipping fetch # git checkout -q -f -B kisskb 3c8ba0d61d04ced9f8d9ff93977995a9e4e96e91 # git clean -qxdf # < git log -1 # commit 3c8ba0d61d04ced9f8d9ff93977995a9e4e96e91 # Author: Kees Cook # Date: Fri Mar 30 18:52:36 2018 -0700 # # kernel.h: Retain constant expression output for max()/min() # # In the effort to remove all VLAs from the kernel[1], it is desirable to # build with -Wvla. However, this warning is overly pessimistic, in that # it is only happy with stack array sizes that are declared as constant # expressions, and not constant values. One case of this is the # evaluation of the max() macro which, due to its construction, ends up # converting constant expression arguments into a constant value result. # # All attempts to rewrite this macro with __builtin_constant_p() failed # with older compilers (e.g. gcc 4.4)[2]. However, Martin Uecker, # constructed[3] a mind-shattering solution that works everywhere. # Cthulhu fhtagn! # # This patch updates the min()/max() macros to evaluate to a constant # expression when called on constant expression arguments. This removes # several false-positive stack VLA warnings from an x86 allmodconfig build # when -Wvla is added: # # $ diff -u before.txt after.txt | grep ^- # -drivers/input/touchscreen/cyttsp4_core.c:871:2: warning: ISO C90 forbids variable length array ‘ids’ [-Wvla] # -fs/btrfs/tree-checker.c:344:4: warning: ISO C90 forbids variable length array ‘namebuf’ [-Wvla] # -lib/vsprintf.c:747:2: warning: ISO C90 forbids variable length array ‘sym’ [-Wvla] # -net/ipv4/proc.c:403:2: warning: ISO C90 forbids variable length array ‘buff’ [-Wvla] # -net/ipv6/proc.c:198:2: warning: ISO C90 forbids variable length array ‘buff’ [-Wvla] # -net/ipv6/proc.c:218:2: warning: ISO C90 forbids variable length array ‘buff64’ [-Wvla] # # This also updates two cases where different enums were being compared # and explicitly casts them to int (which matches the old side-effect of # the single-evaluation code): one in tpm/tpm_tis_core.h, and one in # drm/drm_color_mgmt.c. # # [1] https://lkml.org/lkml/2018/3/7/621 # [2] https://lkml.org/lkml/2018/3/10/170 # [3] https://lkml.org/lkml/2018/3/20/845 # # Co-Developed-by: Linus Torvalds # Co-Developed-by: Martin Uecker # Signed-off-by: Kees Cook # Acked-by: Ingo Molnar # Acked-by: Miguel Ojeda # Signed-off-by: Linus Torvalds # < /opt/cross/kisskb/gcc-4.6.3-nolibc/m68k-linux/bin/m68k-linux-gcc --version # < git log --format=%s --max-count=1 3c8ba0d61d04ced9f8d9ff93977995a9e4e96e91 # < make -s -j 48 ARCH=m68k O=/kisskb/build/linus_sun3_defconfig_m68k CROSS_COMPILE=/opt/cross/kisskb/gcc-4.6.3-nolibc/m68k-linux/bin/m68k-linux- sun3_defconfig arch/m68k/configs/sun3_defconfig:94:warning: symbol value 'm' invalid for NF_TABLES_INET arch/m68k/configs/sun3_defconfig:95:warning: symbol value 'm' invalid for NF_TABLES_NETDEV arch/m68k/configs/sun3_defconfig:200:warning: symbol value 'm' invalid for NF_TABLES_ARP arch/m68k/configs/sun3_defconfig:255:warning: symbol value 'm' invalid for NF_TABLES_BRIDGE WARNING: unmet direct dependencies detected for NEED_MULTIPLE_NODES Depends on [n]: DISCONTIGMEM [=n] || NUMA Selected by [y]: - SINGLE_MEMORY_CHUNK [=y] && MMU [=y] WARNING: unmet direct dependencies detected for NEED_MULTIPLE_NODES Depends on [n]: DISCONTIGMEM [=n] || NUMA Selected by [y]: - SINGLE_MEMORY_CHUNK [=y] && MMU [=y] # make -s -j 48 ARCH=m68k O=/kisskb/build/linus_sun3_defconfig_m68k CROSS_COMPILE=/opt/cross/kisskb/gcc-4.6.3-nolibc/m68k-linux/bin/m68k-linux- WARNING: unmet direct dependencies detected for NEED_MULTIPLE_NODES Depends on [n]: DISCONTIGMEM [=n] || NUMA Selected by [y]: - SINGLE_MEMORY_CHUNK [=y] && MMU [=y] WARNING: unmet direct dependencies detected for NEED_MULTIPLE_NODES Depends on [n]: DISCONTIGMEM [=n] || NUMA Selected by [y]: - SINGLE_MEMORY_CHUNK [=y] && MMU [=y] :1239:2: warning: #warning syscall seccomp not implemented [-Wcpp] :1317:2: warning: #warning syscall pkey_mprotect not implemented [-Wcpp] :1320:2: warning: #warning syscall pkey_alloc not implemented [-Wcpp] :1323:2: warning: #warning syscall pkey_free not implemented [-Wcpp] /kisskb/src/kernel/acct.c: In function 'acct_pin_kill': /kisskb/src/kernel/acct.c:177:2: warning: value computed is not used [-Wunused-value] /kisskb/src/kernel/printk/printk.c: In function 'devkmsg_sysctl_set_loglvl': /kisskb/src/kernel/printk/printk.c:183:16: warning: 'old' may be used uninitialized in this function [-Wuninitialized] /kisskb/src/ipc/shm.c: In function 'ksys_shmdt': /kisskb/src/ipc/shm.c:1607:59: warning: 'file' may be used uninitialized in this function [-Wuninitialized] /kisskb/src/kernel/bpf/syscall.c:1229:12: warning: 'bpf_prog_attach_check_attach_type' defined but not used [-Wunused-function] /kisskb/src/lib/rhashtable.c: In function 'rht_deferred_worker': /kisskb/src/lib/rhashtable.c:269:2: warning: 'next' may be used uninitialized in this function [-Wuninitialized] /kisskb/src/lib/rhashtable.c:234:28: note: 'next' was declared here /kisskb/src/lib/mpi/mpicoder.c: In function 'mpi_read_raw_from_sgl': /kisskb/src/lib/mpi/mpicoder.c:336:12: warning: 'buff' may be used uninitialized in this function [-Wuninitialized] /kisskb/src/fs/ocfs2/file.c: In function 'ocfs2_file_write_iter': /kisskb/src/fs/ocfs2/file.c:2386:3: warning: value computed is not used [-Wunused-value] /kisskb/src/fs/posix_acl.c: In function 'get_acl': /kisskb/src/fs/posix_acl.c:147:3: warning: value computed is not used [-Wunused-value] /kisskb/src/fs/udf/unicode.c: In function 'udf_name_conv_char': /kisskb/src/fs/udf/unicode.c:157:15: warning: 'c' may be used uninitialized in this function [-Wuninitialized] /kisskb/src/drivers/net/ethernet/i825xx/sun3_82586.c: In function 'sun3_82586_timeout': /kisskb/src/drivers/net/ethernet/i825xx/sun3_82586.c:992:89: warning: array subscript is above array bounds [-Warray-bounds] /kisskb/src/net/core/gen_stats.c: In function '__gnet_stats_copy_basic': /kisskb/src/net/core/gen_stats.c:149:19: warning: 'seq' may be used uninitialized in this function [-Wuninitialized] /kisskb/src/drivers/net/macsec.c: In function 'macsec_del_rxsa': /kisskb/src/drivers/net/macsec.c:1926:2: warning: 'assoc_num' may be used uninitialized in this function [-Wuninitialized] /kisskb/src/drivers/net/macsec.c:1926:2: warning: 'rx_sc' may be used uninitialized in this function [-Wuninitialized] /kisskb/src/drivers/net/macsec.c: In function 'macsec_del_txsa': /kisskb/src/drivers/net/macsec.c:2003:2: warning: 'assoc_num' may be used uninitialized in this function [-Wuninitialized] /kisskb/src/drivers/net/macsec.c:2003:2: warning: 'tx_sc' may be used uninitialized in this function [-Wuninitialized] /kisskb/src/drivers/net/macsec.c: In function 'macsec_upd_txsa': /kisskb/src/drivers/net/macsec.c:2068:5: warning: 'assoc_num' may be used uninitialized in this function [-Wuninitialized] /kisskb/src/drivers/net/macsec.c:2068:24: warning: 'tx_sc' may be used uninitialized in this function [-Wuninitialized] /kisskb/src/drivers/net/macsec.c:2069:21: warning: 'secy' may be used uninitialized in this function [-Wuninitialized] /kisskb/src/drivers/net/tun.c: In function 'tun_get_user': /kisskb/src/drivers/net/tun.c:1820:30: warning: 'copylen' may be used uninitialized in this function [-Wuninitialized] /kisskb/src/drivers/net/tun.c:1530:31: warning: 'linear' may be used uninitialized in this function [-Wuninitialized] /kisskb/src/drivers/net/tun.c:1730:46: note: 'linear' was declared here /kisskb/src/net/core/flow_dissector.c: In function '__skb_flow_dissect': /kisskb/src/net/core/flow_dissector.c:789:7: warning: 'vlan' may be used uninitialized in this function [-Wuninitialized] /kisskb/src/net/core/dev.c: In function 'validate_xmit_skb_list': /kisskb/src/net/core/dev.c:3176:15: warning: 'tail' may be used uninitialized in this function [-Wuninitialized] Completed OK # rm -rf /kisskb/build/linus_sun3_defconfig_m68k # Build took: 0:01:04.545692