linux-kernel - [PATCH -next v2 1/2] fs/ntfs3: Don't use uni1 uninitialized in ntfs_d

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Date:   Tue,  4 Oct 2022 16:23:58 -0700
From:   Nathan Chancellor <nathan@...nel.org>
To:     Konstantin Komarov <almaz.alexandrovich@...agon-software.com>
Cc:     Nick Desaulniers <ndesaulniers@...gle.com>,
        Tom Rix <trix@...hat.com>, ntfs3@...ts.linux.dev,
        llvm@...ts.linux.dev, patches@...ts.linux.dev,
        linux-kernel@...r.kernel.org, Nathan Chancellor <nathan@...nel.org>
Subject: [PATCH -next v2 1/2] fs/ntfs3: Don't use uni1 uninitialized in ntfs_d_compare()

Clang warns:

  fs/ntfs3/namei.c:445:7: error: variable 'uni1' is used uninitialized whenever 'if' condition is true [-Werror,-Wsometimes-uninitialized]
                  if (toupper(c1) != toupper(c2)) {
                      ^~~~~~~~~~~~~~~~~~~~~~~~~~
  ./include/linux/ctype.h:64:20: note: expanded from macro 'toupper'
  #define toupper(c) __toupper(c)
                    ^
  fs/ntfs3/namei.c:487:12: note: uninitialized use occurs here
          __putname(uni1);
                    ^~~~
  ./include/linux/fs.h:2789:65: note: expanded from macro '__putname'
  #define __putname(name)         kmem_cache_free(names_cachep, (void *)(name))
                                                                        ^~~~
  fs/ntfs3/namei.c:445:3: note: remove the 'if' if its condition is always false
                  if (toupper(c1) != toupper(c2)) {
                  ^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
  fs/ntfs3/namei.c:434:7: error: variable 'uni1' is used uninitialized whenever 'if' condition is true [-Werror,-Wsometimes-uninitialized]
                  if (!lm--) {
                      ^~~~~
  fs/ntfs3/namei.c:487:12: note: uninitialized use occurs here
          __putname(uni1);
                    ^~~~
  ./include/linux/fs.h:2789:65: note: expanded from macro '__putname'
  #define __putname(name)         kmem_cache_free(names_cachep, (void *)(name))
                                                                        ^~~~
  fs/ntfs3/namei.c:434:3: note: remove the 'if' if its condition is always false
                  if (!lm--) {
                  ^~~~~~~~~~~~
  fs/ntfs3/namei.c:430:22: note: initialize the variable 'uni1' to silence this warning
          struct cpu_str *uni1, *uni2;
                              ^
                              = NULL
  2 errors generated.

There is no point in calling __putname() in these particular error
paths, as there has been no corresponding __getname() call yet. Just
return directly in these blocks to clear up the warning.

Fixes: a3a956c78efa ("fs/ntfs3: Add option "nocase"")
Link: https://github.com/ClangBuiltLinux/linux/issues/1729
Reviewed-by: Nick Desaulniers <ndesaulniers@...gle.com>
Signed-off-by: Nathan Chancellor <nathan@...nel.org>
---

v2:
    * Pick up Nick's reviewed-by tag.
v1: https://lore.kernel.org/20221004144145.1345772-1-nathan@kernel.org/

 fs/ntfs3/namei.c | 12 ++++--------
 1 file changed, 4 insertions(+), 8 deletions(-)

diff --git a/fs/ntfs3/namei.c b/fs/ntfs3/namei.c
index 315763eb05ff..5d3a6ce3f05f 100644
--- a/fs/ntfs3/namei.c
+++ b/fs/ntfs3/namei.c
@@ -431,10 +431,8 @@ static int ntfs_d_compare(const struct dentry *dentry, unsigned int len1,
 
 	/* First try fast implementation. */
 	for (;;) {
-		if (!lm--) {
-			ret = len1 == len2 ? 0 : 1;
-			goto out;
-		}
+		if (!lm--)
+			return len1 == len2 ? 0 : 1;
 
 		if ((c1 = *n1++) == (c2 = *n2++))
 			continue;
@@ -442,10 +440,8 @@ static int ntfs_d_compare(const struct dentry *dentry, unsigned int len1,
 		if (c1 >= 0x80 || c2 >= 0x80)
 			break;
 
-		if (toupper(c1) != toupper(c2)) {
-			ret = 1;
-			goto out;
-		}
+		if (toupper(c1) != toupper(c2))
+			return 1;
 	}
 
 	/*

base-commit: d45da67caedacd500879de5e649360cc70777af7
-- 
2.37.3