> #syz test: git://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git master
This crash does not have a reproducer. I cannot test it.
>
> lib/scatterlist: Fix error handling in extract_iter_to_sg()
>
> Fix the error handling in extract_iter_to_sg(). Pages need to be unpinned,
> not put, and only if they actually got pinned (which is the case in
> extract_user_to_sg()).
>
> The bug may result in a warning like the following:
>
> WARNING: CPU: 1 PID: 20384 at mm/gup.c:229 __lse_atomic_add arch/arm64/include/asm/atomic_lse.h:27 [inline]
> WARNING: CPU: 1 PID: 20384 at mm/gup.c:229 arch_atomic_add arch/arm64/include/asm/atomic.h:28 [inline]
> WARNING: CPU: 1 PID: 20384 at mm/gup.c:229 raw_atomic_add include/linux/atomic/atomic-arch-fallback.h:537 [inline]
> WARNING: CPU: 1 PID: 20384 at mm/gup.c:229 atomic_add include/linux/atomic/atomic-instrumented.h:105 [inline]
> WARNING: CPU: 1 PID: 20384 at mm/gup.c:229 try_grab_page+0x108/0x160 mm/gup.c:252
> ...
> pc : try_grab_page+0x108/0x160 mm/gup.c:229
> lr : follow_page_pte+0x174/0x3e4 mm/gup.c:651
> ...
> Call trace:
> __lse_atomic_add arch/arm64/include/asm/atomic_lse.h:27 [inline]
> arch_atomic_add arch/arm64/include/asm/atomic.h:28 [inline]
> raw_atomic_add include/linux/atomic/atomic-arch-fallback.h:537 [inline]
> atomic_add include/linux/atomic/atomic-instrumented.h:105 [inline]
> try_grab_page+0x108/0x160 mm/gup.c:252
> follow_pmd_mask mm/gup.c:734 [inline]
> follow_pud_mask mm/gup.c:765 [inline]
> follow_p4d_mask mm/gup.c:782 [inline]
> follow_page_mask+0x12c/0x2e4 mm/gup.c:839
> __get_user_pages+0x174/0x30c mm/gup.c:1217
> __get_user_pages_locked mm/gup.c:1448 [inline]
> __gup_longterm_locked+0x94/0x8f4 mm/gup.c:2142
> internal_get_user_pages_fast+0x970/0xb60 mm/gup.c:3140
> pin_user_pages_fast+0x4c/0x60 mm/gup.c:3246
> iov_iter_extract_user_pages lib/iov_iter.c:1768 [inline]
> iov_iter_extract_pages+0xc8/0x54c lib/iov_iter.c:1831
> extract_user_to_sg lib/scatterlist.c:1123 [inline]
> extract_iter_to_sg lib/scatterlist.c:1349 [inline]
> extract_iter_to_sg+0x26c/0x6fc lib/scatterlist.c:1339
> hash_sendmsg+0xc0/0x43c crypto/algif_hash.c:117
> sock_sendmsg_nosec net/socket.c:725 [inline]
> sock_sendmsg+0x54/0x60 net/socket.c:748
> ____sys_sendmsg+0x270/0x2ac net/socket.c:2494
> ___sys_sendmsg+0x80/0xdc net/socket.c:2548
> __sys_sendmsg+0x68/0xc4 net/socket.c:2577
> __do_sys_sendmsg net/socket.c:2586 [inline]
> __se_sys_sendmsg net/socket.c:2584 [inline]
> __arm64_sys_sendmsg+0x24/0x30 net/socket.c:2584
> __invoke_syscall arch/arm64/kernel/syscall.c:38 [inline]
> invoke_syscall+0x48/0x114 arch/arm64/kernel/syscall.c:52
> el0_svc_common.constprop.0+0x44/0xe4 arch/arm64/kernel/syscall.c:142
> do_el0_svc+0x38/0xa4 arch/arm64/kernel/syscall.c:191
> el0_svc+0x2c/0xb0 arch/arm64/kernel/entry-common.c:647
> el0t_64_sync_handler+0xc0/0xc4 arch/arm64/kernel/entry-common.c:665
> el0t_64_sync+0x19c/0x1a0 arch/arm64/kernel/entry.S:591
>
> Fixes: 018584697533 ("netfs: Add a function to extract an iterator into a scatterlist")
> Reported-by: syzbot+9b82859567f2e50c123e@xxxxxxxxxxxxxxxxxxxxxxxxx
> Link: https://lore.kernel.org/linux-mm/000000000000273d0105ff97bf56@xxxxxxxxxx/
> Signed-off-by: David Howells <dhowells@xxxxxxxxxx>
> cc: Sven Schnelle <svens@xxxxxxxxxxxxx>
> cc: akpm@xxxxxxxxxxxxxxxxxxxx
> cc: Herbert Xu <herbert@xxxxxxxxxxxxxxxxxxx>
> cc: "David S. Miller" <davem@xxxxxxxxxxxxx>
> cc: Jeff Layton <jlayton@xxxxxxxxxx>
> cc: Steve French <sfrench@xxxxxxxxx>
> cc: Shyam Prasad N <nspmangalore@xxxxxxxxx>
> cc: Rohith Surabattula <rohiths.msft@xxxxxxxxx>
> cc: Jens Axboe <axboe@xxxxxxxxx>
> cc: Herbert Xu <herbert@xxxxxxxxxxxxxxxxxxx>
> cc: "David S. Miller" <davem@xxxxxxxxxxxxx>
> cc: Eric Dumazet <edumazet@xxxxxxxxxx>
> cc: Jakub Kicinski <kuba@xxxxxxxxxx>
> cc: Paolo Abeni <pabeni@xxxxxxxxxx>
> cc: Matthew Wilcox <willy@xxxxxxxxxxxxx>
> cc: linux-mm@xxxxxxxxx
> cc: linux-crypto@xxxxxxxxxxxxxxx
> cc: linux-cachefs@xxxxxxxxxx
> cc: linux-cifs@xxxxxxxxxxxxxxx
> cc: linux-fsdevel@xxxxxxxxxxxxxxx
> cc: netdev@xxxxxxxxxxxxxxx
> ---
> lib/scatterlist.c | 2 +-
> 1 file changed, 1 insertion(+), 1 deletion(-)
>
> diff --git a/lib/scatterlist.c b/lib/scatterlist.c
> index e86231a44c3d..c65566b4dc66 100644
> --- a/lib/scatterlist.c
> +++ b/lib/scatterlist.c
> @@ -1148,7 +1148,7 @@ static ssize_t extract_user_to_sg(struct iov_iter *iter,
>
> failed:
> while (sgtable->nents > sgtable->orig_nents)
> - put_page(sg_page(&sgtable->sgl[--sgtable->nents]));
> + unpin_user_page(sg_page(&sgtable->sgl[--sgtable->nents]));
> return res;
> }
>
