APPLIED[(K)/J/F]: [PATCH 0/2] md: Replace snprintf with scnprintf

[Stefan Bader]

On 18.10.22 17:13, Tim Gardner wrote:
> BugLink: https://bugs.launchpad.net/bugs/1993315
> 
> SRU Justification
> 
> While this patch was originally requested by the Microsoft Azure team, it seems
> appropriate for the generic kernel as well.
> 
> [Impact]
> Current code produces a warning as shown below when total characters
> in the constituent block device names plus the slashes exceeds 200.
> snprintf() returns the number of characters generated from the given
> input, which could cause the expression “200 – len” to wrap around
> to a large positive number. Fix this by using scnprintf() instead,
> which returns the actual number of characters written into the buffer.
> 
> [ 1513.267938] ------------[ cut here ]------------
> [ 1513.267943] WARNING: CPU: 15 PID: 37247 at <snip>/lib/vsprintf.c:2509 vsnprintf+0x2c8/0x510
> [ 1513.267944] Modules linked in: <snip>
> [ 1513.267969] CPU: 15 PID: 37247 Comm: mdadm Not tainted 5.4.0-1085-azure #90~18.04.1-Ubuntu
> [ 1513.267969] Hardware name: Microsoft Corporation Virtual Machine/Virtual Machine, BIOS Hyper-V UEFI Release v4.1 05/09/2022
> [ 1513.267971] RIP: 0010:vsnprintf+0x2c8/0x510
> <-snip->
> [ 1513.267982] Call Trace:
> [ 1513.267986] snprintf+0x45/0x70
> [ 1513.267990] ? disk_name+0x71/0xa0
> [ 1513.267993] dump_zones+0x114/0x240 [raid0]
> [ 1513.267996] ? _cond_resched+0x19/0x40
> [ 1513.267998] raid0_run+0x19e/0x270 [raid0]
> [ 1513.268000] md_run+0x5e0/0xc50
> [ 1513.268003] ? security_capable+0x3f/0x60
> [ 1513.268005] do_md_run+0x19/0x110
> [ 1513.268006] md_ioctl+0x195e/0x1f90
> [ 1513.268007] blkdev_ioctl+0x91f/0x9f0
> [ 1513.268010] block_ioctl+0x3d/0x50
> [ 1513.268012] do_vfs_ioctl+0xa9/0x640
> [ 1513.268014] ? __fput+0x162/0x260
> [ 1513.268016] ksys_ioctl+0x75/0x80
> [ 1513.268017] __x64_sys_ioctl+0x1a/0x20
> [ 1513.268019] do_syscall_64+0x5e/0x200
> [ 1513.268021] entry_SYSCALL_64_after_hwframe+0x44/0xa9
> 
> [Fix]
> 
> https://git.kernel.org/pub/scm/linux/kernel/git/next/linux-next.git/commit/?id=1727fd5015d8f93474148f94e34cda5aa6ad4a43
> 
> [Where things could go wrong]
> 
> This seems unlikely to cause a regression. At worst the output could be garbled when
> dumping zones.
> 
> [Other Info]
> 
> SF: #00346036
> 
> 
> 

Applied to jammy,focal:linux/master-next. Kinetic was already queued. Thanks.

-Stefan

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