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io_uring/kbuf: use WRITE_ONCE() for userspace-shared buffer ring fields 

buf->addr and buf->len reside in memory shared with userspace. They
should be written with WRITE_ONCE() to guarantee atomic stores and
prevent tearing or other unsafe compiler optimizations.

Signed-off-by: Joanne Koong <joannelkoong@gmail.com>
Cc: Caleb Sander Mateos <csander@purestorage.com>
Signed-off-by: Jens Axboe <axboe@kernel.dk>
pull/1354/merge
Joanne Koong 2025-12-04 15:54:50 -08:00 committed by Jens Axboe
parent 78385c7299
commit a4c694bfc2
1 changed files with 4 additions and 4 deletions
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8
io_uring/kbuf.c
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@ -44,11 +44,11 @@ static bool io_kbuf_inc_commit(struct io_buffer_list *bl, int len)
buf_len -= this_len; buf_len -= this_len;
/* Stop looping for invalid buffer length of 0 */ /* Stop looping for invalid buffer length of 0 */
if (buf_len || !this_len) { if (buf_len || !this_len) {
buf->addr = READ_ONCE(buf->addr) + this_len; WRITE_ONCE(buf->addr, READ_ONCE(buf->addr) + this_len);
buf->len = buf_len; WRITE_ONCE(buf->len, buf_len);
return false; return false;
} }
buf->len = 0; WRITE_ONCE(buf->len, 0);
bl->head++; bl->head++;
len -= this_len; len -= this_len;
} }
@ -291,7 +291,7 @@ static int io_ring_buffers_peek(struct io_kiocb *req, struct buf_sel_arg *arg,
arg->partial_map = 1; arg->partial_map = 1;
if (iov != arg->iovs) if (iov != arg->iovs)
break; break;
buf->len = len; WRITE_ONCE(buf->len, len);
} }
} }