From: HariKrishna Sagala hariconscious@gmail.com

Syzbot reported an uninit-value bug on at kmalloc_reserve for commit 320475fbd590 ("Merge tag 'mtd/fixes-for-6.17-rc6' of git://git.kernel.org/pub/scm/linux/kernel/git/mtd/linux")'

Syzbot KMSAN reported use of uninitialized memory originating from functions "kmalloc_reserve()", where memory allocated via "kmem_cache_alloc_node()" or "kmalloc_node_track_caller()" was not explicitly initialized. This can lead to undefined behavior when the allocated buffer is later accessed.

Fix this by requesting the initialized memory using the gfp flag appended with the option "__GFP_ZERO".

Reported-by: syzbot+9a4fbb77c9d4aacd3388@syzkaller.appspotmail.com Closes: https://syzkaller.appspot.com/bug?extid=9a4fbb77c9d4aacd3388 Fixes: 915d975b2ffa ("net: deal with integer overflows in kmalloc_reserve()") Tested-by: syzbot+9a4fbb77c9d4aacd3388@syzkaller.appspotmail.com Cc: stable@vger.kernel.org # 6.16

Signed-off-by: HariKrishna Sagala hariconscious@gmail.com ---

RESEND: - added Cc stable as suggested from kernel test robot

net/core/skbuff.c | 1 + 1 file changed, 1 insertion(+)

diff --git a/net/core/skbuff.c b/net/core/skbuff.c index ee0274417948..2308ebf99bbd 100644 --- a/net/core/skbuff.c +++ b/net/core/skbuff.c @@ -573,6 +573,7 @@ static void *kmalloc_reserve(unsigned int *size, gfp_t flags, int node, void *obj;

obj_size = SKB_HEAD_ALIGN(*size); + flags |= __GFP_ZERO; if (obj_size <= SKB_SMALL_HEAD_CACHE_SIZE && !(flags & KMALLOC_NOT_NORMAL_BITS)) { obj = kmem_cache_alloc_node(net_hotdata.skb_small_head_cache,