Description
In the Linux kernel, the following vulnerability has been resolved: crash: fix crashkernel resource shrink When crashkernel is configured with a high reservation, shrinking its value below the low crashkernel reservation causes two issues: 1. Invalid crashkernel resource objects 2. Kernel crash if crashkernel shrinking is done twice For example, with crashkernel=200M,high, the kernel reserves 200MB of high memory and some default low memory (say 256MB). The reservation appears as: cat /proc/iomem | grep -i crash af000000-beffffff : Crash kernel 433000000-43f7fffff : Crash kernel If crashkernel is then shrunk to 50MB (echo 52428800 > /sys/kernel/kexec_crash_size), /proc/iomem still shows 256MB reserved: af000000-beffffff : Crash kernel Instead, it should show 50MB: af000000-b21fffff : Crash kernel Further shrinking crashkernel to 40MB causes a kernel crash with the following trace (x86): BUG: kernel NULL pointer dereference, address: 0000000000000038 PGD 0 P4D 0 Oops: 0000 [#1] PREEMPT SMP NOPTI <snip...> Call Trace: <TASK> ? __die_body.cold+0x19/0x27 ? page_fault_oops+0x15a/0x2f0 ? search_module_extables+0x19/0x60 ? search_bpf_extables+0x5f/0x80 ? exc_page_fault+0x7e/0x180 ? asm_exc_page_fault+0x26/0x30 ? __release_resource+0xd/0xb0 release_resource+0x26/0x40 __crash_shrink_memory+0xe5/0x110 crash_shrink_memory+0x12a/0x190 kexec_crash_size_store+0x41/0x80 kernfs_fop_write_iter+0x141/0x1f0 vfs_write+0x294/0x460 ksys_write+0x6d/0xf0 <snip...> This happens because __crash_shrink_memory()/kernel/crash_core.c incorrectly updates the crashk_res resource object even when crashk_low_res should be updated. Fix this by ensuring the correct crashkernel resource object is updated when shrinking crashkernel memory.
Affected products
Version statuses are supplied by the assigning organization. Consult the original record for detailed ranges and platform conditions.
Linux Linux
Default version status: unaffected
16c6006af4d4e70ecef93977a5314409d931020b to < f01f9c348d76d40bf104a94449e3ce4057fdefeeaffected16c6006af4d4e70ecef93977a5314409d931020b to < f89c5e7077f63e45e8ba5a77b7cf0803130367e6affected16c6006af4d4e70ecef93977a5314409d931020b to < a2bd247f8c6c5ac3f0ba823a2fffd77bb9cdf618affected16c6006af4d4e70ecef93977a5314409d931020b to < 00fbff75c5acb4755f06f08bd1071879c63940c5affected
Linux Linux
Default version status: affected
6.5affected0 to < 6.5unaffected6.6.118 to ≤ 6.6.*unaffected6.12.59 to ≤ 6.12.*unaffected6.17.9 to ≤ 6.17.*unaffected6.18 to ≤ *unaffected