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b=aKnUFuClJm5nwOF+zkveF8qfYQ7Ffsj/x2C9dffwv6qelVzIk1T3nOBpfVSceyx5L wg6hLxRqIP0o+j6c+E9iAlGLwuOkghGx5M8JTgc3p0dMl/p9xhM6PFZCIfQHzEIfDa Tp+3rjWZB9cVV85FvM9CApAW43XsByMcfmYez91QaOMpeQEEmb3IOdZaUVSs+iE5KN FIuNfYTfC7MkhbgVD5rjTwwBHYHSO1TksOhJa1QUqepCvRqz6d6jPc2BPfYo9j6SYP 0l8bwCikVLUh7yhf8Vb6QK8vf8LDr8O+g/gd9Y7S+dTxHPiCuCi0QsGqsSsBIVtMVj fJWrzfLGuJa/A== From: Pratyush Yadav To: Breno Leitao Cc: Alexander Graf , Mike Rapoport , Pasha Tatashin , Pratyush Yadav , kexec@lists.infradead.org, linux-mm@kvack.org, linux-kernel@vger.kernel.org, kernel-team@meta.com, stable@vger.kernel.org Subject: Re: [PATCH v2] kho: fix error handling in kho_add_subtree() In-Reply-To: <20260410-kho_fix_send-v2-1-1b4debf7ee08@debian.org> (Breno Leitao's message of "Fri, 10 Apr 2026 02:03:03 -0700") References: <20260410-kho_fix_send-v2-1-1b4debf7ee08@debian.org> Date: Mon, 13 Apr 2026 13:12:20 +0000 Message-ID: <2vxzy0ir80nf.fsf@kernel.org> User-Agent: Gnus/5.13 (Gnus v5.13) MIME-Version: 1.0 Content-Type: text/plain; charset=utf-8 Content-Transfer-Encoding: quoted-printable X-Rspam-User: X-Rspamd-Server: rspam11 X-Rspamd-Queue-Id: A293F80012 X-Stat-Signature: ikca1nwwhmtxk9h3ytef9ukqof8uxdpr X-HE-Tag: 1776085945-673459 X-HE-Meta: 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 lWP6U9na o4rr7eV0aYY4O/GQiXh3htFDRoU3AvuDUoAHs11TjQkN4pQi+8l/qyBBsaga5nyeVBAOvyIzz8y1vRRUs1hIf0L2lV8fcWpr9h8zblhUzv/HaeCrcr9p/9P1pMHzSc+ekndWI2ISnj9D+wDgNtcHtRdGXANQVPATsw0Rz+dHoA4uSCU+68BBviTAouniG8NSnF2zt6os3TWKEYeHsOjdpvY/btcDQtEuidp7ZlKbdW8eZp89xKTAm9FI3+0hFZK+y/brRNIPFLMYQuWXaMMvbtFnX8DdcEv8RabtVCTvVvdrmX98WWS3yWOuC9g== Sender: owner-linux-mm@kvack.org Precedence: bulk X-Loop: owner-majordomo@kvack.org List-ID: List-Subscribe: List-Unsubscribe: On Fri, Apr 10 2026, Breno Leitao wrote: > Fix two error handling issues in kho_add_subtree(), where it doesn't > handle the error path correctly. > > 1. If fdt_setprop() fails after the subnode has been created, the > subnode is not removed. This leaves an incomplete node in the FDT > (missing "preserved-data" or "blob-size" properties). > > 2. The fdt_setprop() return value (an FDT error code) is stored > directly in err and returned to the caller, which expects -errno. > > Fix both by storing fdt_setprop() results in fdt_err, jumping to a new > out_del_node label that removes the subnode on failure, and only setting > err =3D 0 on the success path, otherwise returning -ENOMEM (instead of > FDT_ERR_ errors that would come from fdt_setprop). > > No user-visible changes. This patch fixes error handling in the KHO > (Kexec HandOver) subsystem, which is used to preserve data across kexec > reboots. The fix only affects a rare failure path during kexec > preparation =E2=80=94 specifically when the kernel runs out of space in t= he > Flattened Device Tree buffer while registering preserved memory regions. > > In the unlikely event that this error path was triggered, the old code > would leave a malformed node in the device tree and return an incorrect > error code to the calling subsystem, which could lead to confusing log > messages or incorrect recovery decisions. With this fix, the incomplete > node is properly cleaned up and the appropriate errno value is > propagated, this error code is not returned to the user. > > Cc: stable@vger.kernel.org > Fixes: 3dc92c311498 ("kexec: add Kexec HandOver (KHO) generation helpers") > Suggested-by: Pratyush Yadav > Reviewed-by: Mike Rapoport (Microsoft) > Signed-off-by: Breno Leitao Reviewed-by: Pratyush Yadav [...] --=20 Regards, Pratyush Yadav