nshlib/nsh_fscmds: Fix potential NULL pointer dereferences

[Zepp-Hanzj]

Summary

Fix two potential NULL pointer dereferences in nshlib/nsh_fscmds.c.

Changes

1. fdinfo_callback — NULL deref after asprintf failure

When asprintf() fails (returns < 0), filepath may be NULL. The code logged an error but did not return — it fell through and passed the NULL filepath to nsh_catfile(), causing a NULL pointer dereference.

Fix: Add return ret; after the asprintf error path.

Also fixed a typo in the error message: "nsh_catfaile" → "nsh_catfile".

2. cmd_cat — NULL deref after malloc failure

When argc == 1 (reading from stdin), malloc(BUFSIZ) was called but the return value was never checked. If malloc fails, buf is NULL and nsh_read(vtbl, buf, BUFSIZ) would dereference it.

Fix: Add if (buf == NULL) return -ENOMEM; after the malloc call.

Verification

Built and tested on sim:nsh configuration:

nsh> cat /data/hello.txt
hello

nsh> cat /etc/group
root:*:0:root,admin

nsh> fdinfo 0
FD  OFLAGS  TYPE POS       PATH
0   3       1    0         /dev/console
1   3       1    0         /dev/console
2   3       1    0         /dev/console

nsh> fdinfo 1
FD  OFLAGS  TYPE POS       PATH
0   3       1    0         /dev/console
1   3       1    0         /dev/console
2   3       1    0         /dev/console

nsh> ls -l /data
 -rw-r--r--         152 .version
 -rw-r--r--        1883 .config.backup
 drwxr-xr-x        4096 binfmt/

nsh> help
    .           cmp         false       mkfifo      readlink    time
    [           dirname     fdinfo      mkrd        rm          true

Signed-off-by: hanzhijian hanzhijian@zepp.com