From 211372d63a82861e52250c0f7a5ee78d9dc417ae Mon Sep 17 00:00:00 2001 From: Laszlo Ersek Date: Wed, 24 Feb 2016 21:00:04 +0100 Subject: [PATCH] CryptoPkg: BaseCryptLib: support free(NULL) The ISO C standard says about free(), If ptr is a null pointer, no action occurs. This is not true of the FreePool() interface of the MemoryAllocationLib class: Buffer must have been allocated on a previous call to the pool allocation services of the Memory Allocation Library. [...] If Buffer was not allocated with a pool allocation function in the Memory Allocation Library, then ASSERT(). Therefore we must not forward the argument of free() to FreePool() without checking. This bug can be triggered by upstream OpenSSL commit 8e704858f219 ("RT3955: Reduce some stack usage"), for example. Cc: David Woodhouse Cc: Qin Long Cc: Ting Ye Contributed-under: TianoCore Contribution Agreement 1.0 Signed-off-by: Laszlo Ersek Reviewed-by: Qin Long --- .../Library/BaseCryptLib/SysCall/BaseMemAllocation.c | 8 +++++++- 1 file changed, 7 insertions(+), 1 deletion(-) diff --git a/CryptoPkg/Library/BaseCryptLib/SysCall/BaseMemAllocation.c b/CryptoPkg/Library/BaseCryptLib/SysCall/BaseMemAllocation.c index 544f07215b..964545f143 100644 --- a/CryptoPkg/Library/BaseCryptLib/SysCall/BaseMemAllocation.c +++ b/CryptoPkg/Library/BaseCryptLib/SysCall/BaseMemAllocation.c @@ -38,5 +38,11 @@ void *realloc (void *ptr, size_t size) /* De-allocates or frees a memory block */ void free (void *ptr) { - FreePool (ptr); + // + // In Standard C, free() handles a null pointer argument transparently. This + // is not true of FreePool() below, so protect it. + // + if (ptr != NULL) { + FreePool (ptr); + } }