[PATCH] cmd: nvedit: Validate argument count before use

[Marek Vasut]

Avoid NULL pointer dereference in case 'env select' is invoked
without parameters, check the arg count and make sure it is at
least 2, otherwise print usage.

The crash is easy to trigger e.g. in sandbox:
$ ./u-boot -Tc "env select"

Fixes: a97d22ebba23 ("cmd: env: add env select command")
Signed-off-by: Marek Vasut <marek.vasut+renesas at mailbox.org>
---
Cc: Heinrich Schuchardt <xypron.glpk at gmx.de>
Cc: Ilias Apalodimas <ilias.apalodimas at linaro.org>
Cc: Patrick Delaunay <patrick.delaunay at st.com>
Cc: Tom Rini <trini at konsulko.com>
Cc: Vincent Stehlé <vincent.stehle at arm.com>
Cc: u-boot at lists.denx.de
---
 cmd/nvedit.c | 3 +++
 1 file changed, 3 insertions(+)

diff --git a/cmd/nvedit.c b/cmd/nvedit.c
index 11c3cea882b..636bddee1be 100644
--- a/cmd/nvedit.c
+++ b/cmd/nvedit.c
@@ -499,6 +499,9 @@ static int do_env_load(struct cmd_tbl *cmdtp, int flag, int argc,
 static int do_env_select(struct cmd_tbl *cmdtp, int flag, int argc,
 			 char *const argv[])
 {
+	if (argc < 2)
+		return CMD_RET_USAGE;
+
 	return env_select(argv[1]) ? 1 : 0;
 }
 #endif
-- 
2.51.0