| Message ID | 20230913-strncpy-drivers-firmware-tegra-bpmp-debugfs-c-v1-1-828b0a8914b5@google.com (mailing list archive) |
|---|---|
| State | Mainlined |
| Commit | 9b9056a3137b2e00273f889bfdf498ef6570e332 |
| Headers | show |
| Series | firmware: tegra: bpmp: refactor deprecated strncpy | expand |
On Wed, Sep 13, 2023 at 07:38:44PM +0000, Justin Stitt wrote: > `strncpy` is deprecated for use on NUL-terminated destination strings [1]. > > We should prefer more robust and less ambiguous string interfaces. > > It seems like the filename stored at `namevirt` is expected to be > NUL-terminated. This took me a bit to establish, but yes: buf[256] is used to store filename, so it'll always be %NUL-terminated with the 256 bytes, which is the same size used to allocate virtname, which means it will always be %NUL-terminated. > > A suitable replacement is `strscpy_pad` due to the fact that it > guarantees NUL-termination on the destination buffer whilst maintaining > the NUL-padding behavior that strncpy provides. > > Link: https://www.kernel.org/doc/html/latest/process/deprecated.html#strncpy-on-nul-terminated-strings [1] > Link: https://github.com/KSPP/linux/issues/90 > Cc: linux-hardening@vger.kernel.org > Signed-off-by: Justin Stitt <justinstitt@google.com> This one looks weird because namevirt seems unused, but I assume there's some kind of DMA side-effect happening somewhere? But, yes, after digging around here, I think this all looks right. Reviewed-by: Kees Cook <keescook@chromium.org>
On Wed, 13 Sep 2023 19:38:44 +0000, Justin Stitt wrote: > `strncpy` is deprecated for use on NUL-terminated destination strings [1]. > > We should prefer more robust and less ambiguous string interfaces. > > It seems like the filename stored at `namevirt` is expected to be > NUL-terminated. > > [...] Applied to for-next/hardening, thanks! [1/1] firmware: tegra: bpmp: refactor deprecated strncpy https://git.kernel.org/kees/c/5a4b8c16f53f Take care,
diff --git a/drivers/firmware/tegra/bpmp-debugfs.c b/drivers/firmware/tegra/bpmp-debugfs.c index 6dfe3d34109e..bbcdd9fed3fb 100644 --- a/drivers/firmware/tegra/bpmp-debugfs.c +++ b/drivers/firmware/tegra/bpmp-debugfs.c @@ -610,7 +610,7 @@ static int debugfs_show(struct seq_file *m, void *p) } len = strlen(filename); - strncpy(namevirt, filename, namesize); + strscpy_pad(namevirt, filename, namesize); err = mrq_debugfs_read(bpmp, namephys, len, dataphys, datasize, &nbytes); @@ -661,7 +661,7 @@ static ssize_t debugfs_store(struct file *file, const char __user *buf, } len = strlen(filename); - strncpy(namevirt, filename, namesize); + strscpy_pad(namevirt, filename, namesize); if (copy_from_user(datavirt, buf, count)) { err = -EFAULT;
`strncpy` is deprecated for use on NUL-terminated destination strings [1]. We should prefer more robust and less ambiguous string interfaces. It seems like the filename stored at `namevirt` is expected to be NUL-terminated. A suitable replacement is `strscpy_pad` due to the fact that it guarantees NUL-termination on the destination buffer whilst maintaining the NUL-padding behavior that strncpy provides. Link: https://www.kernel.org/doc/html/latest/process/deprecated.html#strncpy-on-nul-terminated-strings [1] Link: https://github.com/KSPP/linux/issues/90 Cc: linux-hardening@vger.kernel.org Signed-off-by: Justin Stitt <justinstitt@google.com> --- Note: compile tested only. --- drivers/firmware/tegra/bpmp-debugfs.c | 4 ++-- 1 file changed, 2 insertions(+), 2 deletions(-) --- base-commit: 3669558bdf354cd352be955ef2764cde6a9bf5ec change-id: 20230913-strncpy-drivers-firmware-tegra-bpmp-debugfs-c-54f7baaf32c0 Best regards, -- Justin Stitt <justinstitt@google.com>