diff options
| -rw-r--r-- | util-linux/uevent.c | 35 |
1 files changed, 22 insertions, 13 deletions
diff --git a/util-linux/uevent.c b/util-linux/uevent.c index 2f1135f0c..045b35432 100644 --- a/util-linux/uevent.c +++ b/util-linux/uevent.c @@ -30,19 +30,19 @@ #define INIT_G() do { setup_common_bufsiz(); } while (0) enum { MAX_ENV = COMMON_BUFSIZE / sizeof(char*) - 1, - /* sizeof(env[0]) instead of sizeof(char*) - * makes gcc-6.3.0 emit "strict-aliasing" warning. - */ -}; - -enum { - /* socket receive buffer of 2MiB proved to be too small: - * http://lists.busybox.net/pipermail/busybox/2019-December/087665.html - * Udevd seems to use a whooping 128MiB. - * The socket receive buffer size is just a resource limit. - * The buffers are allocated lazily so the memory is not wasted. - */ + // ^^^sizeof(env[0]) instead of sizeof(char*) + // makes gcc-6.3.0 emit "strict-aliasing" warning. + + // socket receive buffer of 2MiB proved to be too small: + // http://lists.busybox.net/pipermail/busybox/2019-December/087665.html + // udevd seems to use a whooping 128MiB. + // The socket receive buffer size is just a resource limit. + // The buffers are allocated lazily so the memory is not wasted. KERN_RCVBUF = 128 * 1024 * 1024, + + // Might be made smaller: the kernel v5.4 passes up to 32 environment + // variables with a total of 2kb on each event. + // On top of that the action string and device path are added. USER_RCVBUF = 16 * 1024, }; @@ -61,6 +61,7 @@ int uevent_main(int argc UNUSED_PARAM, char **argv) // Reproducer: // uevent mdev & // find /sys -name uevent -exec sh -c 'echo add >"{}"' ';' + reopen: fd = create_and_bind_to_netlink(NETLINK_KOBJECT_UEVENT, /*groups:*/ 1 << 0, KERN_RCVBUF); for (;;) { @@ -82,8 +83,16 @@ int uevent_main(int argc UNUSED_PARAM, char **argv) // Here we block, possibly for a very long time len = safe_read(fd, netbuf, USER_RCVBUF - 1); - if (len < 0) + if (len < 0) { + if (errno == ENOBUFS) { + // Ran out of socket receive buffer + bb_simple_error_msg("uevent overrun"); + close(fd); + munmap(netbuf, USER_RCVBUF); + goto reopen; + } bb_simple_perror_msg_and_die("read"); + } end = netbuf + len; *end = '\0'; |