108 lines
3.4 KiB
Diff
108 lines
3.4 KiB
Diff
From aa106b29a6a8a1b0df9e334704292cbc32f2d44e Mon Sep 17 00:00:00 2001
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From: Corinna Vinschen <vinschen@redhat.com>
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Date: Tue, 17 Nov 2020 10:50:57 +0100
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Subject: [PATCH] malloc/nano-malloc: correctly check for out-of-bounds
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allocation reqs
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CVE: CVE-2021-3420
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Reference: https://sourceware.org/git/?p=newlib-cygwin.git;a=commit;h=aa106b29a6a8a1b0df9e334704292cbc32f2d44e
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The overflow check in mEMALIGn erroneously checks for INT_MAX,
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albeit the input parameter is size_t. Fix this to check for
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__SIZE_MAX__ instead. Also, it misses to check the req against
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adding the alignment before calling mALLOc.
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While at it, add out-of-bounds checks to pvALLOc, nano_memalign,
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nano_valloc, and Cygwin's (unused) dlpvalloc.
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Signed-off-by: Corinna Vinschen <corinna@vinschen.de>
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---
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newlib/libc/stdlib/mallocr.c | 7 ++++++-
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newlib/libc/stdlib/nano-mallocr.c | 22 +++++++++++++++++++++-
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winsup/cygwin/malloc.cc | 4 ++++
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3 files changed, 31 insertions(+), 2 deletions(-)
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diff --git a/newlib/libc/stdlib/mallocr.c b/newlib/libc/stdlib/mallocr.c
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index 26d1c89c..af877605 100644
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--- a/newlib/libc/stdlib/mallocr.c
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+++ b/newlib/libc/stdlib/mallocr.c
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@@ -3055,7 +3055,7 @@ Void_t* mEMALIGn(RARG alignment, bytes) RDECL size_t alignment; size_t bytes;
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nb = request2size(bytes);
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/* Check for overflow. */
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- if (nb > INT_MAX || nb < bytes)
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+ if (nb > __SIZE_MAX__ - (alignment + MINSIZE) || nb < bytes)
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{
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RERRNO = ENOMEM;
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return 0;
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@@ -3172,6 +3172,11 @@ Void_t* pvALLOc(RARG bytes) RDECL size_t bytes;
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#endif
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{
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size_t pagesize = malloc_getpagesize;
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+ if (bytes > __SIZE_MAX__ - pagesize)
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+ {
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+ RERRNO = ENOMEM;
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+ return 0;
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+ }
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return mEMALIGn (RCALL pagesize, (bytes + pagesize - 1) & ~(pagesize - 1));
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}
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diff --git a/newlib/libc/stdlib/nano-mallocr.c b/newlib/libc/stdlib/nano-mallocr.c
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index 13b72c99..edf68e7a 100644
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--- a/newlib/libc/stdlib/nano-mallocr.c
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+++ b/newlib/libc/stdlib/nano-mallocr.c
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@@ -568,8 +568,22 @@ void * nano_memalign(RARG size_t align, size_t s)
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if ((align & (align-1)) != 0) return NULL;
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align = MAX(align, MALLOC_ALIGN);
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+
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+ /* Make sure ma_size does not overflow */
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+ if (s > __SIZE_MAX__ - CHUNK_ALIGN)
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+ {
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+ RERRNO = ENOMEM;
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+ return NULL;
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+ }
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ma_size = ALIGN_TO(MAX(s, MALLOC_MINSIZE), CHUNK_ALIGN);
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- size_with_padding = ma_size + align - MALLOC_ALIGN;
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+
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+ /* Make sure size_with_padding does not overflow */
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+ if (ma_size > __SIZE_MAX__ - (align - MALLOC_ALIGN))
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+ {
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+ RERRNO = ENOMEM;
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+ return NULL;
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+ }
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+ size_with_padding = ma_size + (align - MALLOC_ALIGN);
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allocated = nano_malloc(RCALL size_with_padding);
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if (allocated == NULL) return NULL;
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@@ -632,6 +646,12 @@ void * nano_valloc(RARG size_t s)
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#ifdef DEFINE_PVALLOC
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void * nano_pvalloc(RARG size_t s)
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{
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+ /* Make sure size given to nano_valloc does not overflow */
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+ if (s > __SIZE_MAX__ - MALLOC_PAGE_ALIGN)
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+ {
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+ RERRNO = ENOMEM;
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+ return NULL;
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+ }
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return nano_valloc(RCALL ALIGN_TO(s, MALLOC_PAGE_ALIGN));
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}
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#endif /* DEFINE_PVALLOC */
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diff --git a/winsup/cygwin/malloc.cc b/winsup/cygwin/malloc.cc
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index 23c35407..8a1fc257 100644
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--- a/winsup/cygwin/malloc.cc
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+++ b/winsup/cygwin/malloc.cc
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@@ -5298,6 +5298,10 @@ void* dlpvalloc(size_t bytes) {
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size_t pagesz;
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ensure_initialization();
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pagesz = mparams.page_size;
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+ if (bytes > MAX_REQUEST) {
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+ MALLOC_FAILURE_ACTION;
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+ return NULL;
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+ }
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return dlmemalign(pagesz, (bytes + pagesz - SIZE_T_ONE) & ~(pagesz - SIZE_T_ONE));
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}
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--
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2.33.0.windows.2
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