cli/command: Avoid panics after client initialization errors - #7280
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When client.New rejects an invalid Docker host or other client option, it returns a nil concrete client with an error. Returning that pointer directly as client.APIClient stores a typed-nil interface, so lazy version checks dereference it. Return an error instead. Signed-off-by: Paweł Gronowski <pawel.gronowski@docker.com>
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Hm.. nice one indeed. We should probably do some more fixes in this area after this. Initially wasn't able to get it to panic, but it depends on what command you're running; this one reproduces indeed; DOCKER_API_VERSION=1 DOCKER_HOST=:2375 docker version
panic: runtime error: invalid memory address or nil pointer dereference
[signal SIGSEGV: segmentation violation code=0x2 addr=0x58 pc=0x100a31280]
goroutine 1 [running]:
github.com/docker/cli/vendor/github.com/moby/moby/client.(*Client).ClientVersion(0x17cc1292c000?)
/go/src/github.com/docker/cli/vendor/github.com/moby/moby/client/client.go:328
github.com/docker/cli/cli/command.(*DockerCli).CurrentVersion(0x17cc1292c000)
/go/src/github.com/docker/cli/cli/command/cli.go:93 +0x34
github.com/docker/cli/cli/command/system.newClientVersion({0x101101511, 0x7}, {0x101f6c3f0, 0x17cc1292c000})
/go/src/github.com/docker/cli/cli/command/system/version.go:126 +0x168
github.com/docker/cli/cli/command/system.runVersion({0x101f5da80, 0x17cc12918000}, {0x101f6c3f0, 0x17cc1292c000}, 0x101db8f40?)
/go/src/github.com/docker/cli/cli/command/system/version.go:220 +0x5c
github.com/docker/cli/cli/command/system.newVersionCommand.func1(0x0?, {0x0?, 0x0?, 0xf059149abeac7925?})
/go/src/github.com/docker/cli/cli/command/system/version.go:183 +0x2c
main.runDocker.(*DockerCli).InstrumentCobraCommands.func5.2(0x17cc12d65508, {0x10205d6e0, 0x0, 0x0})
/go/src/github.com/docker/cli/cli/command/telemetry_utils.go:58 +0x60
github.com/docker/cli/vendor/github.com/spf13/cobra.(*Command).execute(0x17cc12d65508, {0x17cc12af70b0, 0x0, 0x0})
/go/src/github.com/docker/cli/vendor/github.com/spf13/cobra/command.go:1015 +0x814
github.com/docker/cli/vendor/github.com/spf13/cobra.(*Command).ExecuteC(0x17cc12936008)
/go/src/github.com/docker/cli/vendor/github.com/spf13/cobra/command.go:1148 +0x350
github.com/docker/cli/vendor/github.com/spf13/cobra.(*Command).Execute(...)
/go/src/github.com/docker/cli/vendor/github.com/spf13/cobra/command.go:1071
github.com/docker/cli/vendor/github.com/spf13/cobra.(*Command).ExecuteContext(...)
/go/src/github.com/docker/cli/vendor/github.com/spf13/cobra/command.go:1064
main.runDocker({0x101f5da80, 0x17cc12918000}, 0x17cc1292c000)
/go/src/github.com/docker/cli/cmd/docker/docker.go:544 +0x76c
main.dockerMain({0x101f5d730?, 0x10205d6e0?})
/go/src/github.com/docker/cli/cmd/docker/docker.go:93 +0x13c
main.main()
/go/src/github.com/docker/cli/cmd/docker/docker.go:43 +0x2c |
thaJeztah
reviewed
Sep 3, 2026
| return newAPIClientFromEndpoint(endpoint, configFile, client.WithUserAgent(UserAgent())) | ||
| } | ||
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| func newAPIClientFromEndpoint(ep docker.Endpoint, configFile *configfile.ConfigFile, extraOpts ...client.Opt) (client.APIClient, error) { |
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This one probably also could've keep a concrete type as return.
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- What I did
When client.New rejects an invalid Docker host or other client option, it returns a nil concrete client with an error.
Returning that pointer directly as client.APIClient stores a typed-nil interface, so lazy version checks dereference it.
Return an error instead.
- How I did it
- How to verify it
- Human readable description for the release notes
- A picture of a cute animal (not mandatory but encouraged)