On Wed, 2020-09-16 at 18:02 +0000, KP Singh wrote: > From: KP Singh <[email protected]> > > ima_file_hash can be called when there is no iint->ima_hash available > even though the inode exists in the integrity cache. It is fairly > common for a file to not have a hash. (e.g. an mknodat, prior to the > file being closed). > > Another example where this can happen (suggested by Jann Horn): > > Process A does: > > while(1) { > unlink("/tmp/imafoo"); > fd = open("/tmp/imafoo", O_RDWR|O_CREAT|O_TRUNC, 0700); > if (fd == -1) { > perror("open"); > continue; > } > write(fd, "A", 1); > close(fd); > } > > and Process B does: > > while (1) { > int fd = open("/tmp/imafoo", O_RDONLY); > if (fd == -1) > continue; > char *mapping = mmap(NULL, 0x1000, PROT_READ|PROT_EXEC, > MAP_PRIVATE, fd, 0); > if (mapping != MAP_FAILED) > munmap(mapping, 0x1000); > close(fd); > } > > Due to the race to get the iint->mutex between ima_file_hash and > process_measurement iint->ima_hash could still be NULL. > > Fixes: 6beea7afcc72 ("ima: add the ability to query the cached hash of a > given file") > Signed-off-by: KP Singh <[email protected]> > Reviewed-by: Florent Revest <[email protected]>
Thanks, the patch is queued in next-integrity-testing. Mimi
