From 1e013746544bd1f9df70f5547894fd72719c4b85 Mon Sep 17 00:00:00 2001 From: Thomas Munro Date: Sun, 3 Mar 2024 08:40:41 +1300 Subject: [PATCH] Fix overflow in Windows replacement pg_pread/pg_pwrite. When calling the Windows file I/O APIs there is an implicit conversion from size_t to DWORD, which could overflow. Clamp the size at 1GB to avoid that. Not a really a live bug as we don't expect anything in PostgreSQL to call with such large values. Reviewed-by: Peter Eisentraut Discussion: https://postgr.es/m/1672202.1703441340%40sss.pgh.pa.us --- src/port/win32pread.c | 3 +++ src/port/win32pwrite.c | 3 +++ 2 files changed, 6 insertions(+) diff --git a/src/port/win32pread.c b/src/port/win32pread.c index e1a066fdbe4..2d022e6d378 100644 --- a/src/port/win32pread.c +++ b/src/port/win32pread.c @@ -30,6 +30,9 @@ pg_pread(int fd, void *buf, size_t size, off_t offset) return -1; } + /* Avoid overflowing DWORD. */ + size = Min(size, 1024 * 1024 * 1024); + /* Note that this changes the file position, despite not using it. */ overlapped.Offset = offset; if (!ReadFile(handle, buf, size, &result, &overlapped)) diff --git a/src/port/win32pwrite.c b/src/port/win32pwrite.c index c54bf041bf3..b37bb2f92e0 100644 --- a/src/port/win32pwrite.c +++ b/src/port/win32pwrite.c @@ -30,6 +30,9 @@ pg_pwrite(int fd, const void *buf, size_t size, off_t offset) return -1; } + /* Avoid overflowing DWORD. */ + size = Min(size, 1024 * 1024 * 1024); + /* Note that this changes the file position, despite not using it. */ overlapped.Offset = offset; if (!WriteFile(handle, buf, size, &result, &overlapped))