[go] cmd/go: fix panic in 'go run -C' when flag value is missing

[Ravi Sastry Kadali (Gerrit)]

Ravi Sastry Kadali has uploaded the change for review

Commit message

cmd/go: fix panic in 'go run -C' when flag value is missing

When running 'go run -C' without providing the required directory
argument, `maybeSwitchForGoInstallVersion` panics with a slice bounds
out of range error because it attempts to skip the next argument for
a non-boolean flag without checking whether any arguments remain.

Add a bounds check before consuming the flag's value argument. If no
arguments remain, return early and let the normal command flag parser
report the missing argument error.

Fixes #77483

Change-Id: Ib3d1400df1e641b4ce4a9c353e60dedf6756887e

Change diff

diff --git a/src/cmd/go/internal/toolchain/select.go b/src/cmd/go/internal/toolchain/select.go
index 0cb93f6..4792b47 100644
--- a/src/cmd/go/internal/toolchain/select.go
+++ b/src/cmd/go/internal/toolchain/select.go
@@ -659,6 +659,9 @@
 
 		if bf, ok := f.Value.(interface{ IsBoolFlag() bool }); !ok || !bf.IsBoolFlag() {
 			// The next arg is the value for this flag. Skip it.
+			if len(args) == 0 {
+				return
+			}
 			args = args[1:]
 			continue
 		}
diff --git a/src/cmd/go/testdata/script/run_flag_missing_arg.txt b/src/cmd/go/testdata/script/run_flag_missing_arg.txt
new file mode 100644
index 0000000..bb6d495
--- /dev/null
+++ b/src/cmd/go/testdata/script/run_flag_missing_arg.txt
@@ -0,0 +1,8 @@
+! go run -C
+stderr 'flag needs an argument: -C'
+! stderr 'panic'
+
+# Same for 'go install -C'.
+! go install -C
+stderr 'flag needs an argument: -C'
+! stderr 'panic'
\ No newline at end of file

Change information

Files:

• M src/cmd/go/internal/toolchain/select.go
• A src/cmd/go/testdata/script/run_flag_missing_arg.txt

Change size: S

Delta: 2 files changed, 11 insertions(+), 0 deletions(-)

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[Ravi Sastry Kadali (Gerrit)]

Ravi Sastry Kadali added 1 comment

Patchset-level comments

File-level comment, Patchset 1 (Latest):

Ravi Sastry Kadali . resolved

This is fixed in https://go-review.googlesource.com/c/go/+/742860 so this can be safely closed

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Ravi Sastry Kadali abandoned this change.

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Abandoned https://go-review.googlesource.com/c/go/+/742860 fixes the issue. So this can safely be abandoned

Ravi Sastry Kadali abandoned this change

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