[PATCH 5.10 088/717] firmware: tegra: fix strncpy()/strncat() confusion

Greg Kroah-Hartman
2020-12-28T14:03:39Z

From: Arnd Bergmann <arnd@arndb.de>

[ Upstream commit 9294996f0be40e9da818ed891c82397ab63c00d0 ]

The way that bpmp_populate_debugfs_inband() uses strncpy()
and strncat() makes no sense since the size argument for
the first is insufficient to contain the trailing '/'
and the second passes the length of the input rather than
the output, which triggers a warning:

In function 'strncat',
inlined from 'bpmp_populate_debugfs_inband' at ../drivers/firmware/tegra/bpmp-debugfs.c:422:4:
include/linux/string.h:289:30: warning: '__builtin_strncat' specified bound depends on the length of the source argument [-Wstringop-overflow=]
289 | #define __underlying_strncat __builtin_strncat
| ^
include/linux/string.h:367:10: note: in expansion of macro '__underlying_strncat'
367 | return __underlying_strncat(p, q, count);
| ^~~~~~~~~~~~~~~~~~~~
drivers/firmware/tegra/bpmp-debugfs.c: In function 'bpmp_populate_debugfs_inband':
include/linux/string.h:288:29: note: length computed here
288 | #define __underlying_strlen __builtin_strlen
| ^
include/linux/string.h:321:10: note: in expansion of macro '__underlying_strlen'
321 | return __underlying_strlen(p);

Simplify this to use an snprintf() instead.

Fixes: 5e37b9c137ee ("firmware: tegra: Add support for in-band debug")
Signed-off-by: Arnd Bergmann <arnd@arndb.de>
Acked-by: Jon Hunter <jonathanh@nvidia.com>
Signed-off-by: Thierry Reding <treding@nvidia.com>
Signed-off-by: Sasha Levin <sashal@kernel.org>
---
drivers/firmware/tegra/bpmp-debugfs.c | 6 +-----
1 file changed, 1 insertion(+), 5 deletions(-)

diff --git a/drivers/firmware/tegra/bpmp-debugfs.c b/drivers/firmware/tegra/bpmp-debugfs.c
index c1bbba9ee93a3..440d99c63638b 100644
--- a/drivers/firmware/tegra/bpmp-debugfs.c
+++ b/drivers/firmware/tegra/bpmp-debugfs.c
@@ -412,16 +412,12 @@ static int bpmp_populate_debugfs_inband(struct tegra_bpmp *bpmp,
goto out;
}

- len = strlen(ppath) + strlen(name) + 1;
+ len = snprintf(pathbuf, pathlen, "%s%s/", ppath, name);
if (len >= pathlen) {
err = -EINVAL;
goto out;
}

- strncpy(pathbuf, ppath, pathlen);
- strncat(pathbuf, name, strlen(name));
- strcat(pathbuf, "/");
-
err = bpmp_populate_debugfs_inband(bpmp, dentry,
pathbuf);
if (err < 0)
--
2.27.0