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Tue, 21 Apr 2026 17:11:05 +0000 (UTC) Received: from dovecot-director2.suse.de ([2a07:de40:b281:106:10:150:64:167]) by imap1.dmz-prg2.suse.org with ESMTPSA id XSUFEqmv52m7aAAAD6G6ig (envelope-from ); Tue, 21 Apr 2026 17:11:05 +0000 From: Gabriel Krisman Bertazi To: Jens Axboe Cc: io-uring@vger.kernel.org Subject: Re: [PATCH 4/6] io_uring/rw: add defensive hardening for negative kbuf lengths In-Reply-To: <20260421135626.581917-5-axboe@kernel.dk> (Jens Axboe's message of "Tue, 21 Apr 2026 07:51:41 -0600") References: <20260421135626.581917-1-axboe@kernel.dk> <20260421135626.581917-5-axboe@kernel.dk> Date: Tue, 21 Apr 2026 13:10:59 -0400 Message-ID: <87340oqlwc.fsf@mailhost.krisman.be> User-Agent: Gnus/5.13 (Gnus v5.13) Precedence: bulk X-Mailing-List: io-uring@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Type: text/plain X-Spamd-Result: default: False [-4.29 / 50.00]; BAYES_HAM(-3.00)[100.00%]; NEURAL_HAM_LONG(-1.00)[-1.000]; NEURAL_HAM_SHORT(-0.19)[-0.971]; MIME_GOOD(-0.10)[text/plain]; RCVD_VIA_SMTP_AUTH(0.00)[]; ARC_NA(0.00)[]; MIME_TRACE(0.00)[0:+]; FUZZY_RATELIMITED(0.00)[rspamd.com]; RCPT_COUNT_TWO(0.00)[2]; RCVD_TLS_ALL(0.00)[]; DKIM_SIGNED(0.00)[suse.de:s=susede2_rsa,suse.de:s=susede2_ed25519]; FROM_HAS_DN(0.00)[]; TO_DN_SOME(0.00)[]; FROM_EQ_ENVFROM(0.00)[]; TO_MATCH_ENVRCPT_ALL(0.00)[]; RCVD_COUNT_TWO(0.00)[2]; DBL_BLOCKED_OPENRESOLVER(0.00)[imap1.dmz-prg2.suse.org:helo,kernel.dk:email,suse.de:email] X-Spam-Flag: NO X-Spam-Score: -4.29 X-Spam-Level: Jens Axboe writes: > No real bug here, just being a bit defensive in ensuring that whatever > gets passed into io_put_kbuf() is always >= 0 and not some random error > value. > > Signed-off-by: Jens Axboe > --- > io_uring/rw.c | 4 ++-- > 1 file changed, 2 insertions(+), 2 deletions(-) > > diff --git a/io_uring/rw.c b/io_uring/rw.c > index 20654deff84d..e729e0e7657e 100644 > --- a/io_uring/rw.c > +++ b/io_uring/rw.c > @@ -580,7 +580,7 @@ void io_req_rw_complete(struct io_tw_req tw_req, io_tw_token_t tw) > io_req_io_end(req); > > if (req->flags & (REQ_F_BUFFER_SELECTED|REQ_F_BUFFER_RING)) > - req->cqe.flags |= io_put_kbuf(req, req->cqe.res, NULL); > + req->cqe.flags |= io_put_kbuf(req, max(req->cqe.res, 0), NULL); > > io_req_rw_cleanup(req, 0); > io_req_task_complete(tw_req, tw); > @@ -1379,7 +1379,7 @@ int io_do_iopoll(struct io_ring_ctx *ctx, bool force_nonspin) > list_del(&req->iopoll_node); > wq_list_add_tail(&req->comp_list, &ctx->submit_state.compl_reqs); > nr_events++; > - req->cqe.flags = io_put_kbuf(req, req->cqe.res, NULL); > + req->cqe.flags = io_put_kbuf(req, max(req->cqe.res, 0), NULL); > if (!io_is_uring_cmd(req)) > io_req_rw_cleanup(req, 0); > } Much more readable if it were rolled as an early return inside io_put_kbuf, but clearly: Reviewed-by: Gabriel Krisman Bertazi -- Gabriel Krisman Bertazi