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[167.248.51.36]) by smtp.gmail.com with ESMTPSA id j4-20020a05663822c400b0048881bae098sm1499067jat.156.2024.05.07.12.31.50 for (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Tue, 07 May 2024 12:31:50 -0700 (PDT) From: Bethany Jamison To: kernel-team@lists.ubuntu.com Subject: [SRU][M][PATCH 1/1] firmware: arm_scmi: Fix double free in SMC transport cleanup path Date: Tue, 7 May 2024 14:31:48 -0500 Message-Id: <20240507193149.16501-2-bethany.jamison@canonical.com> X-Mailer: git-send-email 2.34.1 In-Reply-To: <20240507193149.16501-1-bethany.jamison@canonical.com> References: <20240507193149.16501-1-bethany.jamison@canonical.com> MIME-Version: 1.0 X-BeenThere: kernel-team@lists.ubuntu.com X-Mailman-Version: 2.1.20 Precedence: list List-Id: Kernel team discussions List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Errors-To: kernel-team-bounces@lists.ubuntu.com Sender: "kernel-team" From: Andre Przywara [ Upstream commit f1d71576d2c9ec8fdb822173fa7f3de79475e9bd ] When the generic SCMI code tears down a channel, it calls the chan_free callback function, defined by each transport. Since multiple protocols might share the same transport_info member, chan_free() might want to clean up the same member multiple times within the given SCMI transport implementation. In this case, it is SMC transport. This will lead to a NULL pointer dereference at the second time: | scmi_protocol scmi_dev.1: Enabled polling mode TX channel - prot_id:16 | arm-scmi firmware:scmi: SCMI Notifications - Core Enabled. | arm-scmi firmware:scmi: unable to communicate with SCMI | Unable to handle kernel NULL pointer dereference at virtual address 0000000000000000 | Mem abort info: | ESR = 0x0000000096000004 | EC = 0x25: DABT (current EL), IL = 32 bits | SET = 0, FnV = 0 | EA = 0, S1PTW = 0 | FSC = 0x04: level 0 translation fault | Data abort info: | ISV = 0, ISS = 0x00000004, ISS2 = 0x00000000 | CM = 0, WnR = 0, TnD = 0, TagAccess = 0 | GCS = 0, Overlay = 0, DirtyBit = 0, Xs = 0 | user pgtable: 4k pages, 48-bit VAs, pgdp=0000000881ef8000 | [0000000000000000] pgd=0000000000000000, p4d=0000000000000000 | Internal error: Oops: 0000000096000004 [#1] PREEMPT SMP | Modules linked in: | CPU: 4 PID: 1 Comm: swapper/0 Not tainted 6.7.0-rc2-00124-g455ef3d016c9-dirty #793 | Hardware name: FVP Base RevC (DT) | pstate: 61400009 (nZCv daif +PAN -UAO -TCO +DIT -SSBS BTYPE=--) | pc : smc_chan_free+0x3c/0x6c | lr : smc_chan_free+0x3c/0x6c | Call trace: | smc_chan_free+0x3c/0x6c | idr_for_each+0x68/0xf8 | scmi_cleanup_channels.isra.0+0x2c/0x58 | scmi_probe+0x434/0x734 | platform_probe+0x68/0xd8 | really_probe+0x110/0x27c | __driver_probe_device+0x78/0x12c | driver_probe_device+0x3c/0x118 | __driver_attach+0x74/0x128 | bus_for_each_dev+0x78/0xe0 | driver_attach+0x24/0x30 | bus_add_driver+0xe4/0x1e8 | driver_register+0x60/0x128 | __platform_driver_register+0x28/0x34 | scmi_driver_init+0x84/0xc0 | do_one_initcall+0x78/0x33c | kernel_init_freeable+0x2b8/0x51c | kernel_init+0x24/0x130 | ret_from_fork+0x10/0x20 | Code: f0004701 910a0021 aa1403e5 97b91c70 (b9400280) | ---[ end trace 0000000000000000 ]--- Simply check for the struct pointer being NULL before trying to access its members, to avoid this situation. This was found when a transport doesn't really work (for instance no SMC service), the probe routines then tries to clean up, and triggers a crash. Signed-off-by: Andre Przywara Fixes: 1dc6558062da ("firmware: arm_scmi: Add smc/hvc transport") Reviewed-by: Cristian Marussi Link: https://lore.kernel.org/r/20240126122325.2039669-1-andre.przywara@arm.com Signed-off-by: Sudeep Holla Signed-off-by: Sasha Levin (cherry picked from commit 857f56db8c3a71f9871922b6984ff74ad588cb2c linux-6.6.y) CVE-2024-26893 Signed-off-by: Bethany Jamison --- drivers/firmware/arm_scmi/smc.c | 7 +++++++ 1 file changed, 7 insertions(+) diff --git a/drivers/firmware/arm_scmi/smc.c b/drivers/firmware/arm_scmi/smc.c index c193516a254d9..771797b6e2680 100644 --- a/drivers/firmware/arm_scmi/smc.c +++ b/drivers/firmware/arm_scmi/smc.c @@ -196,6 +196,13 @@ static int smc_chan_free(int id, void *p, void *data) struct scmi_chan_info *cinfo = p; struct scmi_smc *scmi_info = cinfo->transport_info; + /* + * Different protocols might share the same chan info, so a previous + * smc_chan_free call might have already freed the structure. + */ + if (!scmi_info) + return 0; + /* Ignore any possible further reception on the IRQ path */ if (scmi_info->irq > 0) free_irq(scmi_info->irq, scmi_info);