From a92df58c26df633770b068e646ebf7053b44db19 Mon Sep 17 00:00:00 2001 From: hselasky Date: Mon, 8 Jun 2020 09:35:32 +0000 Subject: [PATCH] MFC r361827: USB HID descriptors may push/pop the current state to allow description of items residing in a so-called union. FreeBSD currently only supports 4 such push levels. If the push level is not restored within the processing of the same HID item, an invalid memory location may be used for subsequent HID item processing. Verify that the push level is always valid when processing HID items. Reported by: Andy Nguyen (Google) Sponsored by: Mellanox Technologies git-svn-id: svn://svn.freebsd.org/base/stable/9@361922 ccf9f872-aa2e-dd11-9fc8-001c23d0bc1f --- lib/libusbhid/parse.c | 34 +++++++++++++++------------- sys/dev/usb/usb_hid.c | 52 +++++++++++++++++++++---------------------- 2 files changed, 44 insertions(+), 42 deletions(-) diff --git a/lib/libusbhid/parse.c b/lib/libusbhid/parse.c index 7a2b3f41e..943af2696 100644 --- a/lib/libusbhid/parse.c +++ b/lib/libusbhid/parse.c @@ -401,26 +401,28 @@ hid_get_item_raw(hid_data_t s, hid_item_t *h) s->loc_count = dval & mask; break; case 10: /* Push */ + /* stop parsing, if invalid push level */ + if ((s->pushlevel + 1) >= MAXPUSH) + return (0); s->pushlevel ++; - if (s->pushlevel < MAXPUSH) { - s->cur[s->pushlevel] = *c; - /* store size and count */ - c->report_size = s->loc_size; - c->report_count = s->loc_count; - /* update current item pointer */ - c = &s->cur[s->pushlevel]; - } + s->cur[s->pushlevel] = *c; + /* store size and count */ + c->report_size = s->loc_size; + c->report_count = s->loc_count; + /* update current item pointer */ + c = &s->cur[s->pushlevel]; break; case 11: /* Pop */ + /* stop parsing, if invalid push level */ + if (s->pushlevel == 0) + return (0); s->pushlevel --; - if (s->pushlevel < MAXPUSH) { - c = &s->cur[s->pushlevel]; - /* restore size and count */ - s->loc_size = c->report_size; - s->loc_count = c->report_count; - c->report_size = 0; - c->report_count = 0; - } + c = &s->cur[s->pushlevel]; + /* restore size and count */ + s->loc_size = c->report_size; + s->loc_count = c->report_count; + c->report_size = 0; + c->report_count = 0; break; default: break; diff --git a/sys/dev/usb/usb_hid.c b/sys/dev/usb/usb_hid.c index c8a5992c4..9877f6dbf 100644 --- a/sys/dev/usb/usb_hid.c +++ b/sys/dev/usb/usb_hid.c @@ -433,36 +433,36 @@ hid_get_item(struct hid_data *s, struct hid_item *h) s->loc_count = dval & mask; break; case 10: /* Push */ - s->pushlevel ++; - if (s->pushlevel < MAXPUSH) { - s->cur[s->pushlevel] = *c; - /* store size and count */ - c->loc.size = s->loc_size; - c->loc.count = s->loc_count; - /* update current item pointer */ - c = &s->cur[s->pushlevel]; - } else { - DPRINTFN(0, "Cannot push " - "item @ %d\n", s->pushlevel); + /* stop parsing, if invalid push level */ + if ((s->pushlevel + 1) >= MAXPUSH) { + DPRINTFN(0, "Cannot push item @ %d\n", s->pushlevel); + return (0); } + s->pushlevel ++; + s->cur[s->pushlevel] = *c; + /* store size and count */ + c->loc.size = s->loc_size; + c->loc.count = s->loc_count; + /* update current item pointer */ + c = &s->cur[s->pushlevel]; break; case 11: /* Pop */ - s->pushlevel --; - if (s->pushlevel < MAXPUSH) { - /* preserve position */ - oldpos = c->loc.pos; - c = &s->cur[s->pushlevel]; - /* restore size and count */ - s->loc_size = c->loc.size; - s->loc_count = c->loc.count; - /* set default item location */ - c->loc.pos = oldpos; - c->loc.size = 0; - c->loc.count = 0; - } else { - DPRINTFN(0, "Cannot pop " - "item @ %d\n", s->pushlevel); + /* stop parsing, if invalid push level */ + if (s->pushlevel == 0) { + DPRINTFN(0, "Cannot pop item @ 0\n"); + return (0); } + s->pushlevel --; + /* preserve position */ + oldpos = c->loc.pos; + c = &s->cur[s->pushlevel]; + /* restore size and count */ + s->loc_size = c->loc.size; + s->loc_count = c->loc.count; + /* set default item location */ + c->loc.pos = oldpos; + c->loc.size = 0; + c->loc.count = 0; break; default: DPRINTFN(0, "Global bTag=%d\n", bTag); -- 2.42.0