# ReactOS fixes two serious PSEH exception-handling bugs

DevFeed: [ReactOS fixes two serious PSEH exception-handling bugs](<https://devfeed.tech/articles/newsletter-62-32928.md>)

Original publisher: [Read original article](<https://reactos.org/blogs/newsletter-62/>)

Published: 2009-07-21T00:00:00Z

Content type: news

Language: en

Sources: [Front Page on ReactOS Website](<https://devfeed.tech/sources/front-page-on-reactos-website.md>)

Topics: [ReactOS](<https://devfeed.tech/topics/reactos.md>), [exceptions](<https://devfeed.tech/topics/exceptions.md>), [Library](<https://devfeed.tech/topics/library.md>), [Kernel](<https://devfeed.tech/topics/kernel.md>), [gcc](<https://devfeed.tech/topics/gcc.md>)

Tags: [arm](<https://devfeed.tech/tags/arm.md>), [bug](<https://devfeed.tech/tags/bug.md>), [exception-handling](<https://devfeed.tech/tags/exception-handling.md>), [free](<https://devfeed.tech/tags/free.md>), [gcc](<https://devfeed.tech/tags/gcc.md>), [kernel](<https://devfeed.tech/tags/kernel.md>), [library](<https://devfeed.tech/tags/library.md>), [open-source](<https://devfeed.tech/tags/open-source.md>), [os](<https://devfeed.tech/tags/os.md>), [react](<https://devfeed.tech/tags/react.md>), [reactos](<https://devfeed.tech/tags/reactos.md>), [win32](<https://devfeed.tech/tags/win32.md>), [winapi](<https://devfeed.tech/tags/winapi.md>)

## AI overview

ReactOS developers found and fixed two serious bugs in the PSEH library. One mishandled nested try/catch blocks and could cause infinite loops, while the other caused random stack corruption when exceptions were raised.

## Source excerpt

PSEH Corruption In NT operating systems, structured exception handling is used to help safeguard probing of user mode memory buffers and pageable memory while in kernel mode. This requirement was what motivated the creation of the PSEH library by KJK::Hyperion since GCC does not have support for it. Since the last attempt to add SEH support to GCC failed, ReactOS remains dependent on PSEH. Recently, the ARM team committed some code which exposed a very nasty bug in the PSEH library and investigation of the issue led KJK to discover another bug while analyzing the code.