Date: Thu, 23 Jul 2020 19:05:50 +0000 From: bugzilla-noreply@freebsd.org To: bugs@FreeBSD.org Subject: [Bug 248223] Linuxulator: pread behavior differences Message-ID: <bug-248223-227@https.bugs.freebsd.org/bugzilla/>
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https://bugs.freebsd.org/bugzilla/show_bug.cgi?id=248223 Bug ID: 248223 Summary: Linuxulator: pread behavior differences Product: Base System Version: 12.1-RELEASE Hardware: amd64 OS: Any Status: New Severity: Affects Only Me Priority: --- Component: kern Assignee: bugs@FreeBSD.org Reporter: iwtcex@gmail.com % cat pread.c #define _GNU_SOURCE #include <assert.h> #include <errno.h> #include <fcntl.h> #include <stdio.h> #include <string.h> #include <unistd.h> #include <sys/mman.h> void pread_v(int fd, void* buf, size_t nbytes, off64_t offset) { printf("pread(_, _, 0x%lx, _) -> ", nbytes); int ret = pread(fd, buf, nbytes, offset); if (ret != -1) { printf("0x%x\n", ret); } else { printf("%s\n", strerror(errno)); } } int main() { int mem = open("/proc/self/mem", O_RDONLY); assert(mem != -1); char buf[0x4000]; pread_v(mem, buf, 0x1000, 0); // should be EIO printf("---\n"); void* p1 = mmap(NULL, 0x2000, PROT_READ | PROT_WRITE, MAP_ANON | MAP_PRIVATE, -1, 0); void* p2 = mmap(p1 + 0x1000, 0x1000, PROT_NONE, MAP_ANON | MAP_PRIVATE | MAP_FIXED, -1, 0); assert(p1 != MAP_FAILED); assert(p2 == p1 + 0x1000); assert(munmap(p2, 0x1000) == 0); for (int n = sizeof(buf); n >= 0x1000; n /= 2) { pread_v(mem, buf, n, (off64_t)p1); // should return 0x1000 } return 0; } % /compat/linux/bin/gcc -std=c99 -Wall pread.c -o pread % ./pread pread(_, _, 0x1000, _) -> Bad address --- pread(_, _, 0x4000, _) -> Bad address pread(_, _, 0x2000, _) -> Bad address pread(_, _, 0x1000, _) -> 0x1000 On the other hand, Linux (Xubuntu 18.04.3) prints Input/Output errors and 0x1000, 0x1000, 0x1000 there. -- You are receiving this mail because: You are the assignee for the bug.help
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