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Tue, 11 Aug 2026 06:21:47 +0000 (GMT) Received: from [9.123.14.142] (unknown [9.123.14.142]) by smtpav07.fra02v.mail.ibm.com (Postfix) with ESMTP; Tue, 11 Aug 2026 06:21:47 +0000 (GMT) Message-ID: Date: Tue, 11 Aug 2026 11:51:46 +0530 Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 User-Agent: Mozilla Thunderbird Subject: Re: [PATCH] powerpc/kexec_file: Use inclusive range checks in add_usable_mem() To: Thorsten Blum , Madhavan Srinivasan , Michael Ellerman , Nicholas Piggin , "Christophe Leroy (CS GROUP)" , Hari Bathini , Aditya Gupta , Jinjie Ruan , Thiago Jung Bauermann Cc: linuxppc-dev@lists.ozlabs.org, linux-kernel@vger.kernel.org References: <20260809162403.18142-2-thorsten.blum@linux.dev> Content-Language: en-US From: Sourabh Jain In-Reply-To: <20260809162403.18142-2-thorsten.blum@linux.dev> Content-Type: text/plain; charset=UTF-8; format=flowed Content-Transfer-Encoding: 7bit X-TM-AS-GCONF: 00 X-Proofpoint-Reinject: loops=2 maxloops=12 X-Authority-Analysis: v=2.4 cv=RsP16imK c=1 sm=1 tr=0 ts=6a7abf85 cx=c_pps a=3Bg1Hr4SwmMryq2xdFQyZA==:117 a=3Bg1Hr4SwmMryq2xdFQyZA==:17 a=IkcTkHD0fZMA:10 a=Sv0fKeRqtYgA:10 a=VkNPw1HP01LnGYTKEx00:22 a=RnoormkPH1_aCDwRdu11:22 a=RzCfie-kr_QcCd8fBx8p:22 a=q5xIMcLi4I0S6iHGE8EA:9 a=QEXdDO2ut3YA:10 X-Proofpoint-GUID: Pw-NbXelEi3kTYo3v80_gyRVJvy9RnA7 X-Proofpoint-Spam-Details-Enc: AW1haW4tMjYwODExMDA0OCBTYWx0ZWRfX1rbgR83f8s4M /NSvMCAY+Pw4FyHoSIruxwu4uoTrA52/t3TVSfBZCJRSQt1Jp5bCSFmbVjHSdtkCOb4RM1nYOXQ 2Wcd7eIqyiLQNH2HTMrkIJVdhcHrMxGACTgdRI1BMMDJLZ4FTrfPWMvqwwOi8d/ycZpNSHkjwmJ 25N/JhzT4Qw48f/Xy19SkFUu1GyhACsOhv51cMZzBHvs5XDF/CrlXq7WA22tbTINaoVbSpMu/yk ZTYvJPPesxWmXU9xWixCJ9BTQV68ltPV3b5cZBEpRNbT1osofuTuDoQ4LpS9pPW+dn+LpzVIRJ/ 9Efd1/22ONVJiJYN+QqmsxmAjQx0cCP49CtpRwgbVTWEvaHjSmaq1L1O27vOywajc76pbKgo6x6 D6WuTQ6KFpU1QoAyTIHKbeL8EkvFWgf5MpdQUGs2FxrQ3gBI6LkTaDEu1Wv89KykKXFbhzZ+P0W FW1SPjAEUbUTwjlXA6g== X-Proofpoint-ORIG-GUID: BiPUHB2qOTORXGhuuj7bp6UlVG6YgFdg X-Proofpoint-Spam-Info: AW1haW4tMjYwODExMDA0OCBTYWx0ZWRfXw52iODyZ8eJB yNm8+US1RzOXKD++EkNf6uT0rwcnb5FaaKM43j1MgZXiSF6SKbT4OlF6NtG2UeR6AKJZlFdPRtH U6G/mIZaC0YXLagk0gdpRbfTAv30L0o= 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=2026-08-10_06,2026-08-10_03,2025-10-01_01 X-Proofpoint-Spam-Details: rule=outbound_notspam policy=outbound score=0 spamscore=0 impostorscore=0 suspectscore=0 clxscore=1011 malwarescore=0 phishscore=0 adultscore=0 lowpriorityscore=0 priorityscore=1501 bulkscore=0 classifier=typeunknown authscore=0 authtc= authcc= route=outbound adjust=0 reason=mlx scancount=1 engine=8.22.0-2606150000 definitions=main-2608110048 On 09/08/26 21:54, Thorsten Blum wrote: > add_usable_mem() adds usable memory ranges for the kdump kernel. > > The ranges are inclusive, but the partial overlap check uses exclusive > comparisons. This skips ranges with base == loc_end or end == loc_base. > Use inclusive comparisons instead. > > Fixes: 7c64e21a1c5a ("powerpc/kexec_file: Restrict memory usage of kdump kernel") > Signed-off-by: Thorsten Blum > --- > arch/powerpc/kexec/file_load_64.c | 2 +- > 1 file changed, 1 insertion(+), 1 deletion(-) > > diff --git a/arch/powerpc/kexec/file_load_64.c b/arch/powerpc/kexec/file_load_64.c > index 8c72e12ea44e..f9e872693ca7 100644 > --- a/arch/powerpc/kexec/file_load_64.c > +++ b/arch/powerpc/kexec/file_load_64.c > @@ -113,7 +113,7 @@ static int add_usable_mem(struct umem_info *um_info, u64 base, u64 end) > loc_end = um_info->ranges[i].end; > if (loc_base >= base && loc_end <= end) > add = true; > - else if (base < loc_end && end > loc_base) { > + else if (base <= loc_end && end >= loc_base) { This is interesting. The updated condition basically handles exactly a one-byte overlap on either side of the usable memory ranges. In practice, it is very unlikely that we would have such usable memory and LMB ranges. Thorsten, have you encountered any problem that led you to propose this fix? - Sourabh Jain > if (loc_base < base) > loc_base = base; > if (loc_end > end)