5.4-stable review patch. If anyone has any objections, please let me know.
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From: Hamza Mahfooz hamzamahfooz@linux.microsoft.com
commit e6965188f84a7883e6a0d3448e86b0cf29b24dfc upstream.
If the allocation of tl_hba->sh fails in tcm_loop_driver_probe() and we attempt to dereference it in tcm_loop_tpg_address_show() we will get a segfault, see below for an example. So, check tl_hba->sh before dereferencing it.
Unable to allocate struct scsi_host BUG: kernel NULL pointer dereference, address: 0000000000000194 #PF: supervisor read access in kernel mode #PF: error_code(0x0000) - not-present page PGD 0 P4D 0 Oops: 0000 [#1] PREEMPT SMP NOPTI CPU: 1 PID: 8356 Comm: tokio-runtime-w Not tainted 6.6.104.2-4.azl3 #1 Hardware name: Microsoft Corporation Virtual Machine/Virtual Machine, BIOS Hyper-V UEFI Release v4.1 09/28/2024 RIP: 0010:tcm_loop_tpg_address_show+0x2e/0x50 [tcm_loop] ... Call Trace: <TASK> configfs_read_iter+0x12d/0x1d0 [configfs] vfs_read+0x1b5/0x300 ksys_read+0x6f/0xf0 ...
Cc: stable@vger.kernel.org Fixes: 2628b352c3d4 ("tcm_loop: Show address of tpg in configfs") Signed-off-by: Hamza Mahfooz hamzamahfooz@linux.microsoft.com Reviewed-by: Chaitanya Kulkarni kch@nvidia.com Reviewed-by: Allen Pais apais@linux.microsoft.com Link: https://patch.msgid.link/1762370746-6304-1-git-send-email-hamzamahfooz@linux... Signed-off-by: Martin K. Petersen martin.petersen@oracle.com Signed-off-by: Greg Kroah-Hartman gregkh@linuxfoundation.org --- drivers/target/loopback/tcm_loop.c | 3 +++ 1 file changed, 3 insertions(+)
--- a/drivers/target/loopback/tcm_loop.c +++ b/drivers/target/loopback/tcm_loop.c @@ -933,6 +933,9 @@ static ssize_t tcm_loop_tpg_address_show struct tcm_loop_tpg, tl_se_tpg); struct tcm_loop_hba *tl_hba = tl_tpg->tl_hba;
+ if (!tl_hba->sh) + return -ENODEV; + return snprintf(page, PAGE_SIZE, "%d:0:%d\n", tl_hba->sh->host_no, tl_tpg->tl_tpgt); }