# git rev-parse -q --verify 8c7ae38d1ce12a0eaeba655df8562552b3596c7f^{commit}
8c7ae38d1ce12a0eaeba655df8562552b3596c7f
already have revision, skipping fetch
# git checkout -q -f -B kisskb 8c7ae38d1ce12a0eaeba655df8562552b3596c7f
# git clean -qxdf
# < git log -1
# commit 8c7ae38d1ce12a0eaeba655df8562552b3596c7f
# Author: David Howells <dhowells@redhat.com>
# Date:   Wed Mar 27 22:48:02 2019 +0000
# 
#     afs: Fix StoreData op marshalling
#     
#     The marshalling of AFS.StoreData, AFS.StoreData64 and YFS.StoreData64 calls
#     generated by ->setattr() ops for the purpose of expanding a file is
#     incorrect due to older documentation incorrectly describing the way the RPC
#     'FileLength' parameter is meant to work.
#     
#     The older documentation says that this is the length the file is meant to
#     end up at the end of the operation; however, it was never implemented this
#     way in any of the servers, but rather the file is truncated down to this
#     before the write operation is effected, and never expanded to it (and,
#     indeed, it was renamed to 'TruncPos' in 2014).
#     
#     Fix this by setting the position parameter to the new file length and doing
#     a zero-lengh write there.
#     
#     The bug causes Xwayland to SIGBUS due to unexpected non-expansion of a file
#     it then mmaps.  This can be tested by giving the following test program a
#     filename in an AFS directory:
#     
#             #include <stdio.h>
#             #include <stdlib.h>
#             #include <unistd.h>
#             #include <fcntl.h>
#             #include <sys/mman.h>
#             int main(int argc, char *argv[])
#             {
#                     char *p;
#                     int fd;
#                     if (argc != 2) {
#                             fprintf(stderr,
#                                     "Format: test-trunc-mmap <file>\n");
#                             exit(2);
#                     }
#                     fd = open(argv[1], O_RDWR | O_CREAT | O_TRUNC);
#                     if (fd < 0) {
#                             perror(argv[1]);
#                             exit(1);
#                     }
#                     if (ftruncate(fd, 0x140008) == -1) {
#                             perror("ftruncate");
#                             exit(1);
#                     }
#                     p = mmap(NULL, 4096, PROT_READ | PROT_WRITE,
#                              MAP_SHARED, fd, 0);
#                     if (p == MAP_FAILED) {
#                             perror("mmap");
#                             exit(1);
#                     }
#                     p[0] = 'a';
#                     if (munmap(p, 4096) < 0) {
#                             perror("munmap");
#                             exit(1);
#                     }
#                     if (close(fd) < 0) {
#                             perror("close");
#                             exit(1);
#                     }
#                     exit(0);
#             }
#     
#     Fixes: 31143d5d515e ("AFS: implement basic file write support")
#     Reported-by: Jonathan Billings <jsbillin@umich.edu>
#     Tested-by: Jonathan Billings <jsbillin@umich.edu>
#     Signed-off-by: David Howells <dhowells@redhat.com>
#     Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
# < /opt/cross/kisskb/fe-x86-64-core-i7-2017.05/bin/x86_64-linux-gcc --version
# < /opt/cross/kisskb/fe-x86-64-core-i7-2017.05/bin/x86_64-linux-ld --version
# < git log --format=%s --max-count=1 8c7ae38d1ce12a0eaeba655df8562552b3596c7f
# < make -s -j 48 ARCH=um O=/kisskb/build/linus_um-defconfig_um-x86_64 CROSS_COMPILE=/opt/cross/kisskb/fe-x86-64-core-i7-2017.05/bin/x86_64-linux- SUBARCH=x86_64 defconfig
# make -s -j 48 ARCH=um O=/kisskb/build/linus_um-defconfig_um-x86_64 CROSS_COMPILE=/opt/cross/kisskb/fe-x86-64-core-i7-2017.05/bin/x86_64-linux- SUBARCH=x86_64 
/kisskb/src/arch/um/kernel/skas/uaccess.c: In function 'do_op_one_page':
/kisskb/src/arch/um/kernel/skas/uaccess.c:62:10: warning: unused variable 'buf' [-Wunused-variable]
  jmp_buf buf;
          ^
/kisskb/src/arch/um/os-Linux/umid.c: In function 'is_umdir_used':
/kisskb/src/arch/um/os-Linux/umid.c:138:2: warning: ISO C90 forbids variable length array 'file' [-Wvla]
  char file[strlen(uml_dir) + UMID_LEN + sizeof("/pid\0")];
  ^
/kisskb/src/arch/um/os-Linux/umid.c: In function 'create_pid_file':
/kisskb/src/arch/um/os-Linux/umid.c:213:2: warning: ISO C90 forbids variable length array 'file' [-Wvla]
  char file[strlen(uml_dir) + UMID_LEN + sizeof("/pid\0")];
  ^
/kisskb/src/arch/um/os-Linux/umid.c: In function 'remove_umid_dir':
/kisskb/src/arch/um/os-Linux/umid.c:388:2: warning: ISO C90 forbids variable length array 'dir' [-Wvla]
  char dir[strlen(uml_dir) + UMID_LEN + 1], err;
  ^
/kisskb/src/mm/mprotect.c: In function 'change_pte_range':
/kisskb/src/mm/mprotect.c:42:20: warning: unused variable 'mm' [-Wunused-variable]
  struct mm_struct *mm = vma->vm_mm;
                    ^
  LINK linux
Completed OK
# rm -rf /kisskb/build/linus_um-defconfig_um-x86_64
# Build took: 0:00:36.830435