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Fix potential OOB read in zend_dirname() on Windows #16995

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Fix potential OOB read in zend_dirname() on Windows #16995

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503c971
Fix potential OOB read in zend_dirname() on Windows
cmb69 Nov 29, 2024
3cc3ba3
Update Zend/zend_virtual_cwd.h
cmb69 Nov 29, 2024
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6 changes: 3 additions & 3 deletions Zend/zend_compile.c
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Original file line number Diff line number Diff line change
Expand Up @@ -1997,7 +1997,7 @@ ZEND_API size_t zend_dirname(char *path, size_t len)
}

/* Strip trailing slashes */
while (end >= path && IS_SLASH_P(end)) {
while (end >= path && IS_SLASH_P_EX(end, end == path)) {
end--;
}
if (end < path) {
Expand All @@ -2008,7 +2008,7 @@ ZEND_API size_t zend_dirname(char *path, size_t len)
}

/* Strip filename */
while (end >= path && !IS_SLASH_P(end)) {
while (end >= path && !IS_SLASH_P_EX(end, end == path)) {
end--;
}
if (end < path) {
Expand All @@ -2019,7 +2019,7 @@ ZEND_API size_t zend_dirname(char *path, size_t len)
}

/* Strip slashes which came before the file name */
while (end >= path && IS_SLASH_P(end)) {
while (end >= path && IS_SLASH_P_EX(end, end == path)) {
end--;
}
if (end < path) {
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5 changes: 5 additions & 0 deletions Zend/zend_virtual_cwd.h
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Original file line number Diff line number Diff line change
Expand Up @@ -73,8 +73,11 @@ typedef unsigned short mode_t;
#define DEFAULT_SLASH '\\'
#define DEFAULT_DIR_SEPARATOR ';'
#define IS_SLASH(c) ((c) == '/' || (c) == '\\')
// IS_SLASH_P() may read the previous char on Windows, which may be OOB; use IS_SLASH_P_EX() instead
#define IS_SLASH_P(c) (*(c) == '/' || \
(*(c) == '\\' && !IsDBCSLeadByte(*(c-1))))
#define IS_SLASH_P_EX(c, first_byte) (*(c) == '/' || \
(*(c) == '\\' && ((first_byte) || !IsDBCSLeadByte(*(c-1)))))

/* COPY_WHEN_ABSOLUTE is 2 under Win32 because by chance both regular absolute paths
in the file system and UNC paths need copying of two characters */
Expand All @@ -98,7 +101,9 @@ typedef unsigned short mode_t;
#endif

#define IS_SLASH(c) ((c) == '/')
// IS_SLASH_P() may read the previous char on Windows, which may be OOB; use IS_SLASH_P_EX() instead
#define IS_SLASH_P(c) (*(c) == '/')
#define IS_SLASH_P_EX(c, first_byte) (*(c) == '/')

#endif

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