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Subject[PATCH] um: Remove strlcpy declaration
Date
strlcpy() reads the entire source buffer first.
This read may exceed the destination size limit.
This is both inefficient and can lead to linear read
overflows if a source string is not NUL-terminated [1].
In an effort to remove strlcpy() completely [2], replace
strlcpy() here with strscpy().
No return values were used, so direct replacement is safe.

[1] https://www.kernel.org/doc/html/latest/process/deprecated.html#strlcpy
[2] https://github.com/KSPP/linux/issues/89

Signed-off-by: Azeem Shaikh <azeemshaikh38@gmail.com>
---
arch/um/include/shared/user.h | 1 -
arch/um/os-Linux/umid.c | 6 +++---
2 files changed, 3 insertions(+), 4 deletions(-)

diff --git a/arch/um/include/shared/user.h b/arch/um/include/shared/user.h
index 0347a190429c..981e11d8e025 100644
--- a/arch/um/include/shared/user.h
+++ b/arch/um/include/shared/user.h
@@ -50,7 +50,6 @@ static inline int printk(const char *fmt, ...)
#endif

extern int in_aton(char *str);
-extern size_t strlcpy(char *, const char *, size_t);
extern size_t strlcat(char *, const char *, size_t);
extern size_t strscpy(char *, const char *, size_t);

diff --git a/arch/um/os-Linux/umid.c b/arch/um/os-Linux/umid.c
index 7a1abb829930..288c422bfa96 100644
--- a/arch/um/os-Linux/umid.c
+++ b/arch/um/os-Linux/umid.c
@@ -40,7 +40,7 @@ static int __init make_uml_dir(void)
__func__);
goto err;
}
- strlcpy(dir, home, sizeof(dir));
+ strscpy(dir, home, sizeof(dir));
uml_dir++;
}
strlcat(dir, uml_dir, sizeof(dir));
@@ -243,7 +243,7 @@ int __init set_umid(char *name)
if (strlen(name) > UMID_LEN - 1)
return -E2BIG;

- strlcpy(umid, name, sizeof(umid));
+ strscpy(umid, name, sizeof(umid));

return 0;
}
@@ -262,7 +262,7 @@ static int __init make_umid(void)
make_uml_dir();

if (*umid == '\0') {
- strlcpy(tmp, uml_dir, sizeof(tmp));
+ strscpy(tmp, uml_dir, sizeof(tmp));
strlcat(tmp, "XXXXXX", sizeof(tmp));
fd = mkstemp(tmp);
if (fd < 0) {
--
2.41.0.255.g8b1d071c50-goog

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