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Mon, 26 Oct 2026 17:44:16 +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 5UVDAHCR32ptBgAAD6G6ig (envelope-from ); Mon, 26 Oct 2026 17:44:16 +0000 From: Fernando Fernandez Mancera To: netdev@vger.kernel.org Cc: jacob.e.keller@intel.com, horms@kernel.org, pabeni@redhat.com, kuba@kernel.org, edumazet@kernel.org, davem@davemloft.net, jiri@resnulli.us, Fernando Fernandez Mancera , Guikun Yang Subject: [PATCH net] devlink: region: fix snapshot id leak on kernel-allocated ids Date: Mon, 26 Oct 2026 18:44:03 +0100 Message-ID: <20261026174403.512-1-fmancera@suse.de> X-Mailer: git-send-email 2.51.0 X-Mailing-List: netdev@vger.kernel.org List-Id: List-Post: List-Help: List-Subscribe: List-Unsubscribe: List-Owner: Precedence: list MIME-Version: 1.0 Content-Transfer-Encoding: 8bit X-Spamd-Result: default: False [-12.01 / 50.00]; SUSE_INTERNAL_BYPASS(-9.00)[]; BAYES_HAM(-3.00)[100.00%]; NEURAL_HAM_LONG(-1.00)[-1.000]; MID_CONTAINS_FROM(1.00)[]; R_MISSING_CHARSET(0.50)[]; R_DKIM_ALLOW(-0.20)[suse.de:s=susede2_rsa,suse.de:s=susede2_ed25519]; NEURAL_HAM_SHORT(-0.20)[-1.000]; MIME_GOOD(-0.10)[text/plain]; MX_GOOD(-0.01)[]; MIME_TRACE(0.00)[0:+]; DKIM_SIGNED(0.00)[suse.de:s=susede2_rsa,suse.de:s=susede2_ed25519]; ARC_NA(0.00)[]; TO_MATCH_ENVRCPT_ALL(0.00)[]; RBL_SPAMHAUS_BLOCKED_OPENRESOLVER(0.00)[2a07:de40:b281:104:10:150:64:97:from]; FREEMAIL_CC(0.00)[intel.com,kernel.org,redhat.com,davemloft.net,resnulli.us,suse.de,qq.com]; DKIM_TRACE(0.00)[suse.de:+]; TO_DN_SOME(0.00)[]; FROM_EQ_ENVFROM(0.00)[]; RCVD_COUNT_TWO(0.00)[2]; FROM_HAS_DN(0.00)[]; RCVD_TLS_ALL(0.00)[]; DBL_BLOCKED_OPENRESOLVER(0.00)[imap1.dmz-prg2.suse.org:rdns,imap1.dmz-prg2.suse.org:helo,qq.com:email,suse.de:email,suse.de:dkim]; RCPT_COUNT_SEVEN(0.00)[10]; DNSWL_BLOCKED(0.00)[2a07:de40:b281:106:10:150:64:167:received]; RCVD_VIA_SMTP_AUTH(0.00)[]; RECEIVED_SPAMHAUS_BLOCKED_OPENRESOLVER(0.00)[2a07:de40:b281:106:10:150:64:167:received]; FREEMAIL_ENVRCPT(0.00)[qq.com] X-Rspamd-Server: rspamd1.dmz-prg2.suse.org X-Rspamd-Action: no action X-Spam-Flag: NO X-Spam-Score: -12.01 X-Spam-Level: X-Rspamd-Queue-Id: DCF3422254 When DEVLINK_CMD_REGION_NEW is issued without a snapshot id, the kernel allocates one with __devlink_region_snapshot_id_get(). That helper counts the caller as a user of the id, and the caller must release this hold once it is done. devlink_nl_region_new_doit() never drops it. The refcount of the id goes 1 (allocation) -> 2 (snapshot created) and stays at 2. When the snapshot is deleted the count only drops to 1, so the id is never erased from the snapshot_ids xarray. The id then stays in use for the lifetime of the devlink instance: requesting a snapshot with that explicit id fails with -EEXIST, and there is no snapshot left to delete to clean it up. Reproducer steps: # devlink region new pci/0000:13:00.0/device-caps pci/0000:13:00.0/device-caps: snapshot 0 # devlink region del pci/0000:13:00.0/device-caps snapshot 0 # devlink region new pci/0000:13:00.0/device-caps snapshot 0 kernel answers: File exists Drop the caller's reference right after the snapshot has been created, as the snapshot then holds its own. Fixes: 043b3e22768d ("devlink: let kernel allocate region snapshot id") Reported-by: Guikun Yang Closes: https://lore.kernel.org/netdev/tencent_BE912BA710539F285F9FCF28E854ABEFCD07@qq.com/ Signed-off-by: Fernando Fernandez Mancera --- net/devlink/region.c | 5 +++++ 1 file changed, 5 insertions(+) diff --git a/net/devlink/region.c b/net/devlink/region.c index 537779bbff07..c22016f23a4a 100644 --- a/net/devlink/region.c +++ b/net/devlink/region.c @@ -719,6 +719,11 @@ int devlink_nl_region_new_doit(struct sk_buff *skb, struct genl_info *info) if (!snapshot_id_attr) { struct sk_buff *msg; + /* Drop the allocation reference, the snapshot + * now holds its own. + */ + __devlink_snapshot_id_decrement(devlink, snapshot_id); + snapshot = devlink_region_snapshot_get_by_id(region, snapshot_id); if (WARN_ON(!snapshot)) { -- 2.56.0