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Mon, 24 Aug 2026 07:09:43 -0700 (PDT) X-Received: by 2002:a05:6830:82aa:b0:7f3:9729:a9e3 with SMTP id 46e09a7af769-7f462bce15amr25970068a34.7.1787580583002; Mon, 24 Aug 2026 07:09:43 -0700 (PDT) Received: from [192.168.0.6] ([49.204.106.1]) by smtp.gmail.com with ESMTPSA id 46e09a7af769-7f48fb1db63sm4886236a34.12.2026.08.24.07.09.39 (version=TLS1_3 cipher=TLS_AES_128_GCM_SHA256 bits=128/128); Mon, 24 Aug 2026 07:09:42 -0700 (PDT) Message-ID: <5d4e4e0b-3180-4ad9-90ad-2cb0482fc87b@oss.qualcomm.com> Date: Mon, 24 Aug 2026 19:39:38 +0530 Precedence: bulk X-Mailing-List: linux-serial@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 User-Agent: Mozilla Thunderbird Subject: Re: [PATCH] serial: qcom-geni: Drop unsafe rx_buf realloc from setup_fifos() To: Greg Kroah-Hartman Cc: konrad.dybcio@oss.qualcomm.com, Jiri Slaby , chandana.chiluveru@oss.qualcomm.com, linux-arm-msm@vger.kernel.org, linux-kernel@vger.kernel.org, linux-serial@vger.kernel.org, Praveen Talari References: <20260824-drop-unsafe-rx-buf-realloc-from-setup-fifos-v1-1-52d231c840e1@oss.qualcomm.com> <2026082458-lung-knelt-e760@gregkh> Content-Language: en-US From: Praveen Talari In-Reply-To: <2026082458-lung-knelt-e760@gregkh> Content-Type: text/plain; charset=UTF-8; format=flowed Content-Transfer-Encoding: 7bit X-Authority-Analysis: v=2.4 cv=Cfg4Irrl c=1 sm=1 tr=0 ts=6a8c50a8 cx=c_pps a=+3WqYijBVYhDct2f5Fivkw==:117 a=3DKySdf3VQHjbkfL60kt6A==:17 a=IkcTkHD0fZMA:10 a=Sv0fKeRqtYgA:10 a=s4-Qcg_JpJYA:10 a=VkNPw1HP01LnGYTKEx00:22 a=u7WPNUs3qKkmUXheDGA7:22 a=DJpcGTmdVt4CTyJn9g5Z:22 a=EUspDBNiAAAA:8 a=bwh0WvZscbM7pm4pYAQA:9 a=QEXdDO2ut3YA:10 a=eYe2g0i6gJ5uXG_o6N4q:22 X-Proofpoint-Spam-Info: AW1haW4tMjYwODI0MDExOCBTYWx0ZWRfX9F8UbCYhj0qp C4FXPg7vfRMyeGp6FTXZZsfYT0VAJOjJD/7nTI2ZJQI7KciTQ7vgdoq/pNWLeX+YT9BAWj1HNqH YE9alRHx0b4qURs1T1t8Cu7b9+iMarY= X-Proofpoint-Spam-Details-Enc: AW1haW4tMjYwODI0MDExOCBTYWx0ZWRfX6HaI1rwifUDR b1efaM5kuwGlXB/p9YmjY4r1roLw7wSjAp+8v2e1Oq2JRISnvFjPavzBEDT5uOgVmoXAWbct5RA 28TULpPPbxFpPtCZfm19YkgvNzhMhHtrr2UpB2KwsfNqA4+PNPcejyQzoiNP0S5CDwBIzhwtTDl jyA1bBLcJgq8LKzbFi2Ec+2jgLeFgGx/21ZF7YL+k9S2i4ZzRSS3JYlyBd6D0e+EpBMJ/XENdq7 29h7re1NLrOBSggpFJBrH9iIK9d4Rz2vb4AeM3OW4eA9saG6Bipv7qpwnvV1zuEXu6aw75++wFv V99riXIyjsQzuFZik9UeHBPPcUixekvKNd4q3K+uDMUF963P27HNqsuvq0NqY9i1+CF8WYuNJhg HdPQNnJskAFSSUDkxydLJbQ1Rvuh1PBBuID08b0wjC1r7dNiUF9eHyIIGGMGAYO8/jhLxPh5Axg 5C2oBAnBcHSvdg7mNeA== X-Proofpoint-ORIG-GUID: J1t-hr4cyKdEIukHGdXJqdbxjx5UmJgs X-Proofpoint-GUID: J1t-hr4cyKdEIukHGdXJqdbxjx5UmJgs X-Proofpoint-Virus-Version: vendor=baseguard engine=ICAP:2.0.293,Aquarius:18.0.1176,Hydra:6.1.134,FMLib:17.12.100.49 definitions=2026-08-24_04,2026-08-24_01,2025-10-01_01 X-Proofpoint-Spam-Details: rule=outbound_notspam policy=outbound score=0 adultscore=0 phishscore=0 impostorscore=0 spamscore=0 suspectscore=0 priorityscore=1501 malwarescore=0 clxscore=1015 lowpriorityscore=0 bulkscore=0 classifier=typeunknown authscore=0 authtc= authcc= route=outbound adjust=0 reason=mlx scancount=1 engine=8.22.0-2606150000 definitions=main-2608240118 Hi On 24-08-2026 18:26, Greg Kroah-Hartman wrote: > On Mon, Aug 24, 2026 at 04:15:14PM +0530, Praveen Talari wrote: >> The RX buffer is allocated once during probe using a fixed DMA_RX_BUF_SIZE >> and is DMA-mapped for the lifetime of the port. However, setup_fifos() >> attempts to reallocate rx_buf whenever the reported RX FIFO depth changes. >> Since the DMA mapping is not re-established after reallocation, the buffer >> pointer may change while the DMA engine continues using the stale DMA >> address. This can result in RX DMA targeting memory that no longer >> corresponds to the active buffer, leading to invalid DMA accesses and >> potential memory corruption. >> >> The RX FIFO depth is unrelated to the size of rx_buf. The buffer is >> allocated independently using DMA_RX_BUF_SIZE and all RX DMA paths consume >> it at that fixed size. As such, resizing the buffer based on FIFO depth >> changes provides no functional benefit. >> >> Signed-off-by: Praveen Talari >> --- >> Signed-off-by: Praveen Talari > Why is this signed-off-by twice, with different email addresses? Apologies, that was a mistake while updating the commit message. Only praveen.talari@oss.qualcomm.com should be present for upstream submissions. I'll fix it in the next revision Thanks, Praveen Talari > > confused, > > greg k-h