io_uring: prevent re-read of sqe->opcode
Liu reports that he can trigger a NULL pointer dereference with IORING_OP_SENDMSG, by changing the sqe->opcode after we've validated that the previous opcode didn't need a file and didn't assign one. Ensure we validate and read the opcode only once. Reported-by: Liu Yong <pkfxxxing@gmail.com> Tested-by: Liu Yong <pkfxxxing@gmail.com> Signed-off-by: Jens Axboe <axboe@kernel.dk> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
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@ -279,6 +279,7 @@ struct sqe_submit {
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bool has_user;
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bool needs_lock;
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bool needs_fixed_file;
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u8 opcode;
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};
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/*
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@ -505,7 +506,7 @@ static inline void io_queue_async_work(struct io_ring_ctx *ctx,
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int rw = 0;
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if (req->submit.sqe) {
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switch (req->submit.sqe->opcode) {
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switch (req->submit.opcode) {
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case IORING_OP_WRITEV:
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case IORING_OP_WRITE_FIXED:
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rw = !(req->rw.ki_flags & IOCB_DIRECT);
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@ -1254,23 +1255,15 @@ static int io_import_fixed(struct io_ring_ctx *ctx, int rw,
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}
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static ssize_t io_import_iovec(struct io_ring_ctx *ctx, int rw,
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const struct sqe_submit *s, struct iovec **iovec,
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struct io_kiocb *req, struct iovec **iovec,
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struct iov_iter *iter)
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{
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const struct io_uring_sqe *sqe = s->sqe;
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const struct io_uring_sqe *sqe = req->submit.sqe;
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void __user *buf = u64_to_user_ptr(READ_ONCE(sqe->addr));
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size_t sqe_len = READ_ONCE(sqe->len);
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u8 opcode;
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/*
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* We're reading ->opcode for the second time, but the first read
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* doesn't care whether it's _FIXED or not, so it doesn't matter
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* whether ->opcode changes concurrently. The first read does care
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* about whether it is a READ or a WRITE, so we don't trust this read
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* for that purpose and instead let the caller pass in the read/write
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* flag.
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*/
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opcode = READ_ONCE(sqe->opcode);
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opcode = req->submit.opcode;
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if (opcode == IORING_OP_READ_FIXED ||
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opcode == IORING_OP_WRITE_FIXED) {
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ssize_t ret = io_import_fixed(ctx, rw, sqe, iter);
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@ -1278,7 +1271,7 @@ static ssize_t io_import_iovec(struct io_ring_ctx *ctx, int rw,
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return ret;
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}
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if (!s->has_user)
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if (!req->submit.has_user)
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return -EFAULT;
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#ifdef CONFIG_COMPAT
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@ -1425,7 +1418,7 @@ static int io_read(struct io_kiocb *req, const struct sqe_submit *s,
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if (unlikely(!(file->f_mode & FMODE_READ)))
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return -EBADF;
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ret = io_import_iovec(req->ctx, READ, s, &iovec, &iter);
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ret = io_import_iovec(req->ctx, READ, req, &iovec, &iter);
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if (ret < 0)
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return ret;
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@ -1490,7 +1483,7 @@ static int io_write(struct io_kiocb *req, const struct sqe_submit *s,
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if (unlikely(!(file->f_mode & FMODE_WRITE)))
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return -EBADF;
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ret = io_import_iovec(req->ctx, WRITE, s, &iovec, &iter);
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ret = io_import_iovec(req->ctx, WRITE, req, &iovec, &iter);
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if (ret < 0)
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return ret;
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@ -2109,15 +2102,14 @@ static int io_req_defer(struct io_ring_ctx *ctx, struct io_kiocb *req,
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static int __io_submit_sqe(struct io_ring_ctx *ctx, struct io_kiocb *req,
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const struct sqe_submit *s, bool force_nonblock)
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{
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int ret, opcode;
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int ret;
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req->user_data = READ_ONCE(s->sqe->user_data);
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if (unlikely(s->index >= ctx->sq_entries))
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return -EINVAL;
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opcode = READ_ONCE(s->sqe->opcode);
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switch (opcode) {
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switch (req->submit.opcode) {
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case IORING_OP_NOP:
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ret = io_nop(req, req->user_data);
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break;
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@ -2181,10 +2173,10 @@ static int __io_submit_sqe(struct io_ring_ctx *ctx, struct io_kiocb *req,
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return 0;
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}
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static struct async_list *io_async_list_from_sqe(struct io_ring_ctx *ctx,
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const struct io_uring_sqe *sqe)
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static struct async_list *io_async_list_from_req(struct io_ring_ctx *ctx,
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struct io_kiocb *req)
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{
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switch (sqe->opcode) {
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switch (req->submit.opcode) {
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case IORING_OP_READV:
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case IORING_OP_READ_FIXED:
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return &ctx->pending_async[READ];
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@ -2196,12 +2188,10 @@ static struct async_list *io_async_list_from_sqe(struct io_ring_ctx *ctx,
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}
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}
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static inline bool io_sqe_needs_user(const struct io_uring_sqe *sqe)
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static inline bool io_req_needs_user(struct io_kiocb *req)
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{
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u8 opcode = READ_ONCE(sqe->opcode);
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return !(opcode == IORING_OP_READ_FIXED ||
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opcode == IORING_OP_WRITE_FIXED);
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return !(req->submit.opcode == IORING_OP_READ_FIXED ||
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req->submit.opcode == IORING_OP_WRITE_FIXED);
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}
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static void io_sq_wq_submit_work(struct work_struct *work)
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@ -2217,7 +2207,7 @@ static void io_sq_wq_submit_work(struct work_struct *work)
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int ret;
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old_cred = override_creds(ctx->creds);
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async_list = io_async_list_from_sqe(ctx, req->submit.sqe);
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async_list = io_async_list_from_req(ctx, req);
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allow_kernel_signal(SIGINT);
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restart:
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@ -2239,7 +2229,7 @@ restart:
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}
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ret = 0;
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if (io_sqe_needs_user(sqe) && !cur_mm) {
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if (io_req_needs_user(req) && !cur_mm) {
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if (!mmget_not_zero(ctx->sqo_mm)) {
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ret = -EFAULT;
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} else {
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@ -2387,11 +2377,9 @@ static bool io_add_to_prev_work(struct async_list *list, struct io_kiocb *req)
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return ret;
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}
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static bool io_op_needs_file(const struct io_uring_sqe *sqe)
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static bool io_op_needs_file(struct io_kiocb *req)
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{
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int op = READ_ONCE(sqe->opcode);
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switch (op) {
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switch (req->submit.opcode) {
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case IORING_OP_NOP:
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case IORING_OP_POLL_REMOVE:
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case IORING_OP_TIMEOUT:
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@ -2419,7 +2407,7 @@ static int io_req_set_file(struct io_ring_ctx *ctx, const struct sqe_submit *s,
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*/
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req->sequence = s->sequence;
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if (!io_op_needs_file(s->sqe))
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if (!io_op_needs_file(req))
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return 0;
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if (flags & IOSQE_FIXED_FILE) {
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@ -2460,7 +2448,7 @@ static int __io_queue_sqe(struct io_ring_ctx *ctx, struct io_kiocb *req,
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s->sqe = sqe_copy;
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memcpy(&req->submit, s, sizeof(*s));
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list = io_async_list_from_sqe(ctx, s->sqe);
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list = io_async_list_from_req(ctx, req);
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if (!io_add_to_prev_work(list, req)) {
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if (list)
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atomic_inc(&list->cnt);
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@ -2582,7 +2570,7 @@ err:
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req->user_data = s->sqe->user_data;
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#if defined(CONFIG_NET)
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switch (READ_ONCE(s->sqe->opcode)) {
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switch (req->submit.opcode) {
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case IORING_OP_SENDMSG:
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case IORING_OP_RECVMSG:
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spin_lock(¤t->fs->lock);
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@ -2697,6 +2685,7 @@ static bool io_get_sqring(struct io_ring_ctx *ctx, struct sqe_submit *s)
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if (head < ctx->sq_entries) {
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s->index = head;
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s->sqe = &ctx->sq_sqes[head];
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s->opcode = READ_ONCE(s->sqe->opcode);
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s->sequence = ctx->cached_sq_head;
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ctx->cached_sq_head++;
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return true;
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