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: 979a6e28dd96 ("udf: Get rid of 0-length arrays in struct fileIdentDesc") Signed-off-by: Jan Kara jack@suse.cz --- fs/udf/namei.c | 8 ++++---- 1 file changed, 4 insertions(+), 4 deletions(-)

diff --git a/fs/udf/namei.c b/fs/udf/namei.c index 0ed4861b038f..b3d5f97f16cd 100644 --- a/fs/udf/namei.c +++ b/fs/udf/namei.c @@ -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); }