udf: Avoid using stale lengthOfImpUse

udf_write_fi() uses lengthOfImpUse of the entry it is writing to.
However this field has not yet been initialized so it either contains
completely bogus value or value from last directory entry at that place.
In either case this is wrong and can lead to filesystem corruption or
kernel crashes.

Reported-by: butt3rflyh4ck <butterflyhuangxx@gmail.com>
CC: stable@vger.kernel.org
Fixes: 979a6e28dd ("udf: Get rid of 0-length arrays in struct fileIdentDesc")
Signed-off-by: Jan Kara <jack@suse.cz>
This commit is contained in:
Jan Kara 2022-05-10 12:36:04 +02:00
parent 846a3351dd
commit c1ad35dd05

View File

@ -75,11 +75,11 @@ int udf_write_fi(struct inode *inode, struct fileIdentDesc *cfi,
if (fileident) {
if (adinicb || (offset + lfi < 0)) {
memcpy(udf_get_fi_ident(sfi), fileident, lfi);
memcpy(sfi->impUse + liu, fileident, lfi);
} else if (offset >= 0) {
memcpy(fibh->ebh->b_data + offset, fileident, lfi);
} else {
memcpy(udf_get_fi_ident(sfi), fileident, -offset);
memcpy(sfi->impUse + liu, fileident, -offset);
memcpy(fibh->ebh->b_data, fileident - offset,
lfi + offset);
}
@ -88,11 +88,11 @@ int udf_write_fi(struct inode *inode, struct fileIdentDesc *cfi,
offset += lfi;
if (adinicb || (offset + padlen < 0)) {
memset(udf_get_fi_ident(sfi) + lfi, 0x00, padlen);
memset(sfi->impUse + liu + lfi, 0x00, padlen);
} else if (offset >= 0) {
memset(fibh->ebh->b_data + offset, 0x00, padlen);
} else {
memset(udf_get_fi_ident(sfi) + lfi, 0x00, -offset);
memset(sfi->impUse + liu + lfi, 0x00, -offset);
memset(fibh->ebh->b_data, 0x00, padlen + offset);
}