Please try current git, it contains a fix. Let me know if it doesn't work.
On Mon, Sep 15, 2025 at 7:57 AM tshah <[email protected]> wrote: > > Hello Denys, > > Can you please look into this change and let me know your thoughts on > this once you get chance. > > Thanks. > > On 09/09/25 15:50, tshah wrote: > > Hello, > > > > This patch address the issue: > > https://lists.busybox.net/pipermail/busybox/2025-September/091718.html. > > The patch replaces the use of vfork() with fork() on MMU-enabled > > targets in the xvfork() macro. > > This change is necessary to resolve a segmentation fault observed on > > ppc64le when running: "unshare -mrpf sh". > > > > According to POSIX, there is an udefined behaviour if the child > > process created by vfork() either modifies the data other than a > > variable of type pid_t or calls any other functions before > > successfully calling exec (3) or _exit(2) family functions. > > From the strace logs,it looks like the child after vfork performed > > syscalls like writing uid_map, gid_map, mounting, etc, which violates > > the minimal action requirements of vfork() resulting in a SIGSEGV > > maybe due to race conditions. > > > > [ 189] [00003fff9376726c] vfork(strace: Process 376786 attached > > <unfinished ...> > > [pid 376786] [ 286] [00003fff936d7a80] openat(AT_FDCWD, > > "/proc/self/setgroups", O_WRONLY) = 3 > > [pid 376786] [ 4] [00003fff936d7a80] write(3, "deny", 4) = 4 > > [pid 376786] [ 6] [00003fff936d7a80] close(3) = 0 > > [pid 376786] [ 286] [00003fff936d7a80] openat(AT_FDCWD, > > "/proc/self/uid_map", O_WRONLY) = 3 > > [pid 376786] [ 4] [00003fff936d7a80] write(3, "0 1000 1", 8) = 8 > > [pid 376786] [ 6] [00003fff936d7a80] close(3) = 0 > > [pid 376786] [ 286] [00003fff936d7a80] openat(AT_FDCWD, > > "/proc/self/gid_map", O_WRONLY) = 3 > > [pid 376786] [ 4] [00003fff936d7a80] write(3, "0 1000 1", 8) = 8 > > [pid 376786] [ 6] [00003fff936d7a80] close(3) = 0 > > [pid 376786] [ 21] [00003fff937890fc] mount("none", "/", NULL, > > MS_REC|MS_PRIVATE, NULL) = 0 > > [pid 376786] [ 11] [00003fff93741230] execve("/usr/local/bin/bash", > > ["bash", "-c", "ls"], 0x3fffe38b2780 /* 22 vars */) = -1 ENOENT (No > > such file or directory) > > [pid 376786] [ 11] [00003fff93741230] execve("/usr/bin/bash", > > ["bash", "-c", "ls"], 0x3fffe38b2780 /* 22 vars */ <unfinished ...> > > [pid 376785] [ 189] [00003fff9376726c] <... vfork resumed>) = 376786 > > [pid 376785] [ 189] [f37838210030e840] --- SIGSEGV {si_signo=SIGSEGV, > > si_code=SEGV_BNDERR, si_addr=0xf37838210030e840, si_lower=NULL, > > si_upper=NULL} --- > > [pid 376786] [ 11] [00003fffaf368aa0] <... execve resumed>) = 0 > > [pid 376786] [ 45] [00003fffaf371188] brk(NULL) = 0x100157a6000 > > [pid 376786] [ 90] [00003fffaf374638] mmap(NULL, 8192, > > PROT_READ|PROT_WRITE, MAP_PRIVATE|MAP_ANONYMOUS, -1, 0) = 0x3fffaf391000 > > [pid 376786] [ 33] [00003fffaf373e90] access("/etc/ld.so.preload", > > R_OK) = -1 ENOENT (No such file or directory) > > [pid 376786] [ 286] [00003fffaf374340] openat(AT_FDCWD, > > "/etc/ld.so.cache", O_RDONLY|O_CLOEXEC) = 3 > > [pid 376785] [ 189] [????????????????] +++ killed by SIGSEGV +++ > > > > > > Replacing vfork() with fork() will eliminate this issue because fork() > > creates a separate memory space, so the child’s operations cannot > > corrupt the parent’s stack and both processes operate independently. > > > > _______________________________________________ > > busybox mailing list > > [email protected] > > https://lists.busybox.net/mailman/listinfo/busybox _______________________________________________ busybox mailing list [email protected] https://lists.busybox.net/mailman/listinfo/busybox
