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QFSFileEngine: fix overflow bug when using lseek64

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QT_LSEEK (lseek64()) returns QT_OFF_T, which is off64_t on 32bit
systems. The return from the lseek64() call was being assigned to an
int, which meant that if the returned value is > INT_MAX it will
overflow and the value becomes -1, and since errno would be EOVERFLOW
the code would fail to open the file.

Fix the issue by assigning the return value to QT_OFF_T.

Thanks to Giuseppe for pointing out the issue in the code review.

Found by compiling with -Wshorten-64-to-32.

[ChangeLog][QtCore][QFile] Fixed a bug where opening a file in append
mode may fail if the file size was bigger than INT_MAX.

Pick-to: 6.5 6.4 6.2 5.15
Change-Id: Iad33e3192f37466643a1218d38e5ecc2baaa7dc9
Reviewed-by: Thiago Macieira <thiago.macieira@intel.com>
This commit is contained in:
Ahmad Samir 2023-03-08 13:49:21 +02:00
parent 0d29a406f7
commit 5bffb47d6e
2 changed files with 2 additions and 2 deletions
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2
src/corelib/io/qfsfileengine.cpp
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@ -328,7 +328,7 @@ bool QFSFileEnginePrivate::openFd(QIODevice::OpenMode openMode, int fd)
// Seek to the end when in Append mode.
if (openMode & QFile::Append) {
int ret;
QT_OFF_T ret;
do {
ret = QT_LSEEK(fd, 0, SEEK_END);
} while (ret == -1 && errno == EINTR);

2
src/corelib/io/qfsfileengine_unix.cpp
View File

@ -115,7 +115,7 @@ bool QFSFileEnginePrivate::nativeOpenImpl(QIODevice::OpenMode openMode, mode_t m
// Seek to the end when in Append mode.
if (flags & QFile::Append) {
int ret;
QT_OFF_T ret;
do {
ret = QT_LSEEK(fd, 0, SEEK_END);
} while (ret == -1 && errno == EINTR);