KMSAN reports an uninitialized value in adiantum_crypt, created at write_begin_get_folio(). New folios are allocated with the FGP_CREAT flag and may be returned uninitialized. These uninitialized folios are then used without proper initialization. Fixes: b799474b9aeb ("mm/pagemap: add write_begin_get_folio() helper function") Tested-by: syzbot+703d8a2cd20971854b06@syzkaller.appspotmail.com Reported-by: syzbot+703d8a2cd20971854b06@syzkaller.appspotmail.com Closes: https://syzkaller.appspot.com/bug?extid=703d8a2cd20971854b06 Signed-off-by: Bartlomiej Kubik --- include/linux/pagemap.h | 3 ++- 1 file changed, 2 insertions(+), 1 deletion(-) diff --git a/include/linux/pagemap.h b/include/linux/pagemap.h index 31a848485ad9..31bbc8299e08 100644 --- a/include/linux/pagemap.h +++ b/include/linux/pagemap.h @@ -787,7 +787,8 @@ static inline struct folio *write_begin_get_folio(const struct kiocb *iocb, fgp_flags |= FGP_DONTCACHE; return __filemap_get_folio(mapping, index, fgp_flags, - mapping_gfp_mask(mapping)); + mapping_gfp_mask(mapping)| + __GFP_ZERO); } /** -- 2.39.5