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Fri, 03 Jul 2026 01:35:08 -0700 (PDT) Received: from [192.168.0.38] ([86.12.216.189]) by smtp.gmail.com with ESMTPSA id 5b1f17b1804b1-493c63ba97csm113763845e9.12.2026.07.03.01.35.07 (version=TLS1_3 cipher=TLS_AES_128_GCM_SHA256 bits=128/128); Fri, 03 Jul 2026 01:35:08 -0700 (PDT) Message-ID: <91a6f517-9e4f-434a-ab65-daadadf00b1a@gmail.com> Date: Fri, 3 Jul 2026 09:35:07 +0100 MIME-Version: 1.0 User-Agent: Mozilla Thunderbird Subject: Re: [PATCH v3] gdb: replace alloca with gdb::unique_xmalloc_ptr in remote-fileio.c Content-Language: en-US To: Pedro Alves , Luis Machado , gdb-patches@sourceware.org Cc: guinevere@redhat.com References: <20260630095238.1700797-1-luis.machado@amd.com> <20260701190156.3900537-1-luis.machado@amd.com> <391c7c82-c658-4122-a006-520232ad3cd8@palves.net> From: Luis In-Reply-To: <391c7c82-c658-4122-a006-520232ad3cd8@palves.net> Content-Type: text/plain; charset=UTF-8; format=flowed Content-Transfer-Encoding: 7bit X-BeenThere: gdb-patches@sourceware.org X-Mailman-Version: 2.1.30 Precedence: list List-Id: Gdb-patches mailing list List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Errors-To: gdb-patches-bounces~public-inbox=simark.ca@sourceware.org On 01/07/2026 20:08, Pedro Alves wrote: > On 2026-07-01 20:01, Luis Machado wrote: >> remote_fileio_extract_ptr_w_len parsed a debuggee controlled 64 bit >> length, narrowed it to int with no bounds check, and the value flowed >> directly into alloca() across RSP File I/O handlers (Fopen, Frename, >> Funlink, Fstat, Fsystem). A malicious inferior or remote stub could >> send a crafted packet with a large path length, displacing the stack >> pointer by up to 2 GiB and potentially crashing the debugger. >> >> remote_fileio_extract_ptr_w_len now rejects negative lengths, lengths >> that would overflow the int result (greater than INT_MAX), and zero. >> An allow_zero_length flag lets the Fsystem handler opt in to the zero >> length sentinel that signals a NULL cmdline query. All other handlers >> use the default and are protected without any per call checks. Oversized >> names are rejected naturally by the underlying syscall with ENAMETOOLONG. >> All alloca(length) calls have been replaced with >> gdb::unique_xmalloc_ptr, so an oversized but positive length now >> fails as a graceful heap allocation error rather than corrupting the >> stack. >> >> Add a selftest that exercises various problematic cases. >> >> Signed-off-by: Luis Machado > > Approved-By: Pedro Alves > Thanks. Pushed now.