| Date | Thu, 22 Apr 2010 12:07:35 -0700 | From | Greg KH <> | Subject | [004/197] fat: fix buffer overflow in vfat_create_shortname() |
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2.6.32-stable review patch. If anyone has any objections, please let us know.
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From: Nikolaus Schulz <microschulz@web.de>
commit 30d1872d9eb3663b4cf7bdebcbf5cd465674cced upstream.
When using the string representation of a random counter as part of the base name, ensure that it is no longer than 4 bytes.
Since we are repeatedly decrementing the counter in a loop until we have found a unique base name, the counter may wrap around zero; therefore, it is not enough to mask its higher bits before entering the loop, this must be done inside the loop.
[hirofumi@mail.parknet.co.jp: use snprintf()] Signed-off-by: Nikolaus Schulz <microschulz@web.de> Signed-off-by: OGAWA Hirofumi <hirofumi@mail.parknet.co.jp> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org> Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>
--- fs/fat/namei_vfat.c | 6 +++--- 1 file changed, 3 insertions(+), 3 deletions(-)
--- a/fs/fat/namei_vfat.c +++ b/fs/fat/namei_vfat.c @@ -309,7 +309,7 @@ static int vfat_create_shortname(struct { struct fat_mount_options *opts = &MSDOS_SB(dir->i_sb)->options; wchar_t *ip, *ext_start, *end, *name_start; - unsigned char base[9], ext[4], buf[8], *p; + unsigned char base[9], ext[4], buf[5], *p; unsigned char charbuf[NLS_MAX_CHARSET_SIZE]; int chl, chi; int sz = 0, extlen, baselen, i, numtail_baselen, numtail2_baselen; @@ -467,7 +467,7 @@ static int vfat_create_shortname(struct return 0; } - i = jiffies & 0xffff; + i = jiffies; sz = (jiffies >> 16) & 0x7; if (baselen > 2) { baselen = numtail2_baselen; @@ -476,7 +476,7 @@ static int vfat_create_shortname(struct name_res[baselen + 4] = '~'; name_res[baselen + 5] = '1' + sz; while (1) { - sprintf(buf, "%04X", i); + snprintf(buf, sizeof(buf), "%04X", i & 0xffff); memcpy(&name_res[baselen], buf, 4); if (vfat_find_form(dir, name_res) < 0) break;
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