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Fix ZipOS deadlock/segfault (#1011)

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This change adds a new stress test for ZipOS which helped
us improve the locking semantics in open() and close().
This commit is contained in:
Jōshin 2023-12-14 22:59:20 -05:00 • committed by GitHub
parent 897fa6ac00
commit 8a10ccf9c4
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GPG key ID: 4AEE18F83AFDEB23
4 changed files with 76 additions and 6 deletions
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15
libc/calls/close.c
View file

@ -21,6 +21,7 @@
#include "libc/calls/internal.h"
#include "libc/calls/state.internal.h"
#include "libc/calls/struct/fd.internal.h"
#include "libc/calls/struct/sigset.internal.h"
#include "libc/calls/syscall-nt.internal.h"
#include "libc/calls/syscall-sysv.internal.h"
#include "libc/dce.h"
@ -91,8 +92,18 @@ static int close_impl(int fd) {
* @vforksafe
*/
int close(int fd) {
int rc = close_impl(fd);
if (!__vforked) __releasefd(fd);
int rc;
if (__isfdkind(fd, kFdZip)) { // XXX IsWindows()?
BLOCK_SIGNALS;
__fds_lock();
rc = close_impl(fd);
if (!__vforked) __releasefd(fd);
__fds_unlock();
ALLOW_SIGNALS;
} else {
rc = close_impl(fd);
if (!__vforked) __releasefd(fd);
}
STRACE("close(%d) → %d% m", fd, rc);
return rc;
}

8
libc/runtime/zipos-open.c
View file

@ -235,21 +235,21 @@ void __zipos_postdup(int oldfd, int newfd) {
if (oldfd == newfd) {
return;
}
BLOCK_SIGNALS;
__fds_lock();
if (__isfdkind(newfd, kFdZip)) {
__zipos_free((struct ZiposHandle *)(intptr_t)g_fds.p[newfd].handle);
if (!__isfdkind(oldfd, kFdZip)) {
__fds_lock();
bzero(g_fds.p + newfd, sizeof(*g_fds.p));
__fds_unlock();
}
}
if (__isfdkind(oldfd, kFdZip)) {
__zipos_keep((struct ZiposHandle *)(intptr_t)g_fds.p[oldfd].handle);
__fds_lock();
__ensurefds_unlocked(newfd);
g_fds.p[newfd] = g_fds.p[oldfd];
__fds_unlock();
}
__fds_unlock();
ALLOW_SIGNALS;
}
/**

1
libc/runtime/zipos-read.c
View file

@ -58,6 +58,7 @@ static ssize_t __zipos_read_impl(struct ZiposHandle *h, const struct iovec *iov,
if (b) memcpy(iov[i].iov_base, h->mem + y, b);
}
if (opt_offset == -1) {
unassert(y != SIZE_MAX);
atomic_store_explicit(&h->pos, y, memory_order_release);
}
return y - x;