From patchwork Sat Jan 18 17:35:31 2025 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 8bit X-Patchwork-Submitter: Michael Tokarev X-Patchwork-Id: 13944229 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org Received: from lists.gnu.org (lists.gnu.org [209.51.188.17]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by smtp.lore.kernel.org (Postfix) with ESMTPS id ABCC5C02185 for ; Sat, 18 Jan 2025 18:22:01 +0000 (UTC) Received: from localhost ([::1] helo=lists1p.gnu.org) by lists.gnu.org with esmtp (Exim 4.90_1) (envelope-from ) id 1tZDRk-0001dz-2T; Sat, 18 Jan 2025 13:21:24 -0500 Received: from eggs.gnu.org ([2001:470:142:3::10]) by lists.gnu.org with esmtps (TLS1.2:ECDHE_RSA_AES_256_GCM_SHA384:256) (Exim 4.90_1) (envelope-from ) id 1tZDRg-0001cB-KP; Sat, 18 Jan 2025 13:21:20 -0500 Received: from isrv.corpit.ru ([86.62.121.231]) by eggs.gnu.org with esmtps (TLS1.2:ECDHE_RSA_AES_256_GCM_SHA384:256) (Exim 4.90_1) (envelope-from ) id 1tZDRd-0003KQ-Vp; Sat, 18 Jan 2025 13:21:20 -0500 Received: from tsrv.corpit.ru (tsrv.tls.msk.ru [192.168.177.2]) by isrv.corpit.ru (Postfix) with ESMTP id B7BA4DA8F8; Sat, 18 Jan 2025 21:20:58 +0300 (MSK) Received: by tsrv.corpit.ru (Postfix, from userid 1000) id 2695C19E94D; Sat, 18 Jan 2025 21:21:09 +0300 (MSK) From: Michael Tokarev Date: Sat, 18 Jan 2025 20:35:31 +0300 Subject: [PATCH] vvfat: refresh writing long filename To: qemu-devel@nongnu.org, Kevin Wolf , Hanna Reitz , =?utf-8?q?Volker_R=C3=BCmelin?= Cc: Pierrick Bouvier , qemu-block@nongnu.org, qemu-trivial@nongnu.org Message-Id: <20250118182109.2695C19E94D@tsrv.corpit.ru> Received-SPF: pass client-ip=86.62.121.231; envelope-from=mjt@corpit.ru; helo=isrv.corpit.ru X-Spam_score_int: -63 X-Spam_score: -6.4 X-Spam_bar: ------ X-Spam_report: (-6.4 / 5.0 requ) BAYES_00=-1.9, HEADER_FROM_DIFFERENT_DOMAINS=0.248, PP_MIME_FAKE_ASCII_TEXT=0.241, RCVD_IN_DNSWL_HI=-5, RCVD_IN_VALIDITY_CERTIFIED_BLOCKED=0.001, RCVD_IN_VALIDITY_RPBL_BLOCKED=0.001, SPF_HELO_NONE=0.001, SPF_PASS=-0.001 autolearn=ham autolearn_force=no X-Spam_action: no action X-BeenThere: qemu-devel@nongnu.org X-Mailman-Version: 2.1.29 Precedence: list List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Errors-To: qemu-devel-bounces+qemu-devel=archiver.kernel.org@nongnu.org Sender: qemu-devel-bounces+qemu-devel=archiver.kernel.org@nongnu.org In function create_long_filname(), the array name[8 + 3] in struct direntry_t is used as if it were defined as name[32]. This is intentional and works. It's nevertheless an out of bounds array access. To avoid this problem, this patch adds a struct lfn_direntry_t with multiple name arrays. A directory entry for a long FAT file name is significantly different from a directory entry for a regular FAT file name. This change makes whole logic dealing with the long filenames a bit more clear (hopefully). Based on ideas by Volker Rümelin. Signed-off-by: Michael Tokarev --- block/vvfat.c | 69 ++++++++++++++++++++++++++++++++------------------- 1 file changed, 43 insertions(+), 26 deletions(-) diff --git a/block/vvfat.c b/block/vvfat.c index 8ffe8b3b9b..8320733045 100644 --- a/block/vvfat.c +++ b/block/vvfat.c @@ -255,6 +255,17 @@ typedef struct direntry_t { uint32_t size; } QEMU_PACKED direntry_t; +typedef struct lfn_direntry_t { + uint8_t sequence; + uint8_t name01[10]; + uint8_t attributes; + uint8_t direntry_type; + uint8_t sfn_checksum; + uint8_t name0e[12]; + uint16_t begin; + uint8_t name1c[4]; +} QEMU_PACKED lfn_direntry_t; + /* this structure are used to transparently access the files */ typedef struct mapping_t { @@ -399,11 +410,22 @@ static void init_mbr(BDRVVVFATState *s, int cyls, int heads, int secs) /* direntry functions */ +static unsigned write_lfn_part(uint8_t *dest, unsigned dsize, + const gunichar2 *lptr, const gunichar2 *lend) +{ + unsigned i; + for(i = 0; i < dsize / 2 && lptr + i < lend; ++i) { + dest[i / 2 + 0] = lptr[i] & 0xff; + dest[i / 2 + 1] = lptr[i] >> 8; + } + return i; /* return number of elements actually written */ +} + static direntry_t *create_long_filename(BDRVVVFATState *s, const char *filename) { - int number_of_entries, i; + unsigned number_of_entries, entidx; + gunichar2 *lptr, *lend; glong length; - direntry_t *entry; gunichar2 *longname = g_utf8_to_utf16(filename, -1, NULL, &length, NULL); if (!longname) { @@ -411,31 +433,26 @@ static direntry_t *create_long_filename(BDRVVVFATState *s, const char *filename) return NULL; } - number_of_entries = DIV_ROUND_UP(length * 2, 26); - - for(i=0;idirectory)); - entry->attributes=0xf; - entry->reserved[0]=0; - entry->begin=0; - entry->name[0]=(number_of_entries-i)|(i==0?0x40:0); - } - for(i=0;i<26*number_of_entries;i++) { - int offset=(i%26); - if(offset<10) offset=1+offset; - else if(offset<22) offset=14+offset-10; - else offset=28+offset-22; - entry=array_get(&(s->directory),s->directory.next-1-(i/26)); - if (i >= 2 * length + 2) { - entry->name[offset] = 0xff; - } else if (i % 2 == 0) { - entry->name[offset] = longname[i / 2] & 0xff; - } else { - entry->name[offset] = longname[i / 2] >> 8; - } + /* + * each lfn_direntry holds 13 utf16 chars (26 bytes) of the file name, + * the name is split into several directory entries. + */ + number_of_entries = DIV_ROUND_UP(length, 13); + + lend = longname + length; /* pointer past the end of longname */ + for(entidx = 0, lptr = longname; entidx < number_of_entries; entidx++) { + lfn_direntry_t *entry = array_get_next(&(s->directory)); + entry->sequence = (number_of_entries - entidx) | (entidx == 0 ? 0x40 : 0); + entry->attributes = 0xf; + entry->direntry_type = 0; + entry->begin = 0; + /* each lftn_direntry has 3 pieces to hold parts of long file name */ + lptr += write_lfn_part(entry->name01, sizeof(entry->name01), lptr, lend); + lptr += write_lfn_part(entry->name0e, sizeof(entry->name0e), lptr, lend); + lptr += write_lfn_part(entry->name1c, sizeof(entry->name1c), lptr, lend); } g_free(longname); - return array_get(&(s->directory),s->directory.next-number_of_entries); + return array_get(&(s->directory), s->directory.next - number_of_entries); } static char is_free(const direntry_t* direntry) @@ -731,7 +748,7 @@ static inline direntry_t* create_short_and_long_name(BDRVVVFATState* s, /* calculate anew, because realloc could have taken place */ entry_long=array_get(&(s->directory),long_index); while(entry_longreserved[1]=chksum; + ((lfn_direntry_t *)entry_long)->sfn_checksum = chksum; entry_long++; } }