Cygwin: dll_init: use SIZE_T instead of DWORD for size

jeremyd2019 · jeremyd2019 · commit 88d3ddbe2ba1 · 2025-05-22T13:35:05.000-07:00
The RegionSize member of the MEMORY_BASIC_INFORMATION struct is of type SIZE_T, and it may be larger than will fit in a DWORD (I observed 0x200000000). This resulted in an error due to trying to reserve 0 bytes from VirtualAllloc. Fixes: 8d777a1 ("* dll_init.cc (reserve_at, release_at): New functions.") Addresses: https://cygwin.com/pipermail/cygwin/2025-May/258154.html Reported-by: Yuyi Wang <Strawberry_Str@hotmail.com> Signed-off-by: Jeremy Drake <cygwin@jdrake.com>
diff --git a/winsup/cygwin/dll_init.cc b/winsup/cygwin/dll_init.cc
@@ -633,7 +633,7 @@ dll_list::track_self ()
 static PVOID
 reserve_at (PCWCHAR name, PVOID here, PVOID dll_base, DWORD dll_size)
 {
-  DWORD size;
+  SIZE_T size;
   MEMORY_BASIC_INFORMATION mb;
 
   if (!VirtualQuery (here, &mb, sizeof (mb)))
diff --git a/winsup/cygwin/release/3.6.2 b/winsup/cygwin/release/3.6.2
@@ -28,3 +28,6 @@ Fixes:
 
 - Fix infinite exception loop on segmentation fault when strace-ing
   Addresses: https://cygwin.com/pipermail/cygwin/2025-May/258144.html
+
+- Fix size truncation in dll_init reserve_at function.
+  Addresses: https://cygwin.com/pipermail/cygwin/2025-May/258154.html

Original file line number	Diff line number	Diff line change
`@@ -633,7 +633,7 @@ dll_list::track_self ()`
`633`	`633`	`static PVOID`
`634`	`634`	`reserve_at (PCWCHAR name, PVOID here, PVOID dll_base, DWORD dll_size)`
`635`	`635`	`{`
`636`		`- DWORD size;`
	`636`	`+ SIZE_T size;`
`637`	`637`	`MEMORY_BASIC_INFORMATION mb;`
`638`	`638`
`639`	`639`	`if (!VirtualQuery (here, &mb, sizeof (mb)))`