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um: Remove strlcpy declaration

PATCH Applied Azeem Shaikh 2 participants 3 messages Jul 3, 2023 – Jul 27, 2023 User-mode Linux (UML)

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Azeem Shaikh

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#0 lore raw

PATCH 1/1 um: Remove strlcpy declaration

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 <[email protected]>
---
 arch/um/include/shared/user.h |    1 -
 arch/um/os-Linux/umid.c       |    6 +++---
 2 files changed, 3 insertions(+), 4 deletions(-)
arch/um/include/shared/user.h +0 -1
index 0347a190429c..981e11d8e025 100644
@@ -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);
arch/um/os-Linux/umid.c +3 -3
index 7a1abb829930..288c422bfa96 100644
@@ -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) {
Signature · 1 line
2.41.0.255.g8b1d071c50-goog
Reviewed-by on v1 1/1
#1 lore raw
Quoted 8 lines · Azeem Shaikh

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.

Quoted 4 lines

[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 <[email protected]>
Reviewed-by Kees Cook <[email protected]>
Signature · 1 line
Kees Cook
Applied
#2 lore raw
In reply to Azeem Shaikh
Quoted 9 lines · Azeem Shaikh

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.

[...]

Applied, thanks!

[1/1] um: Remove strlcpy declaration

      https://git.kernel.org/kees/c/61ce78f29a69

Best regards,

Signature · 1 line
Kees Cook