CVE-2023-53331: 
Linux Kernel vulnerability analysis and mitigation

In the Linux kernel, the following vulnerability has been resolved:

pstore/ram: Check start of empty przs during init

After commit 30696378f68a ("pstore/ram: Do not treat empty buffers as valid"), initialization would assume a prz was valid after seeing that the buffer_size is zero (regardless of the buffer start position). This unchecked start value means it could be outside the bounds of the buffer, leading to future access panics when written to:

sysdumppanicevent+0x3b4/0x5b8 atomicnotifiercallchain+0x54/0x90 panic+0x1c8/0x42c die+0x29c/0x2a8 diekernelfault+0x68/0x78 _dokernelfault+0x1c4/0x1e0 dobadarea+0x40/0x100 dotranslationfault+0x68/0x80 domemabort+0x68/0xf8 el1da+0x1c/0xc0 _rawwriteb+0x38/0x174 _memcpytoio+0x40/0xac persistentramupdate+0x44/0x12c persistentramwrite+0x1a8/0x1b8 ramoopspstorewrite+0x198/0x1e8 pstoreconsole_write+0x94/0xe0 ...

To avoid this, also check if the prz start is 0 during the initialization phase. If not, the next prz sanity check case will discover it (start > size) and zap the buffer back to a sane state.

[kees: update commit log with backtrace and clarifications]