[newlib-cygwin/main] Cygwin: posix_fallocate(3): fix offset and length sanity check

[newlib-cygwin/main] Cygwin: posix_fallocate(3): fix offset and length sanity check

[Corinna Vinschen]

https://sourceware.org/git/gitweb.cgi?p=newlib-cygwin.git;h=295bef07d6bd18cd58746e46b400faadfb54b712

commit 295bef07d6bd18cd58746e46b400faadfb54b712
Author:     Corinna Vinschen <corinna@vinschen.de>
AuthorDate: Tue Dec 5 22:08:01 2023 +0100
Commit:     Corinna Vinschen <corinna@vinschen.de>
CommitDate: Tue Dec 5 22:19:05 2023 +0100

    Cygwin: posix_fallocate(3): fix offset and length sanity check
    
    - len must not be <= 0
    - offset + len must not exceed off_t (max. file size)
    
    Fixes: 7636b5859062 ("* autoload.cc (NtSetInformationFile): Define.")
    Signed-off-by: Corinna Vinschen <corinna@vinschen.de>

Diff:
---
 winsup/cygwin/syscalls.cc | 4 +++-
 1 file changed, 3 insertions(+), 1 deletion(-)

diff --git a/winsup/cygwin/syscalls.cc b/winsup/cygwin/syscalls.cc
index b73391d8f84e..3edb55bc608f 100644
--- a/winsup/cygwin/syscalls.cc
+++ b/winsup/cygwin/syscalls.cc
@@ -3030,8 +3030,10 @@ extern "C" int
 posix_fallocate (int fd, off_t offset, off_t len)
 {
   int res = 0;
-  if (offset < 0 || len == 0)
+  if (offset < 0 || len <= 0)
     res = EINVAL;
+  else if (INT64_MAX - len < offset)
+    res = EFBIG;
   else
     {
       cygheap_fdget cfd (fd);