Description
In the Linux kernel, the following vulnerability has been resolved: scsi: core: Wake up the error handler when final completions race against each other The fragile ordering between marking commands completed or failed so that the error handler only wakes when the last running command completes or times out has race conditions. These race conditions can cause the SCSI layer to fail to wake the error handler, leaving I/O through the SCSI host stuck as the error state cannot advance. First, there is an memory ordering issue within scsi_dec_host_busy(). The write which clears SCMD_STATE_INFLIGHT may be reordered with reads counting in scsi_host_busy(). While the local CPU will see its own write, reordering can allow other CPUs in scsi_dec_host_busy() or scsi_eh_inc_host_failed() to see a raised busy count, causing no CPU to see a host busy equal to the host_failed count. This race condition can be prevented with a memory barrier on the error path to force the write to be visible before counting host busy commands. Second, there is a general ordering issue with scsi_eh_inc_host_failed(). By counting busy commands before incrementing host_failed, it can race with a final command in scsi_dec_host_busy(), such that scsi_dec_host_busy() does not see host_failed incremented but scsi_eh_inc_host_failed() counts busy commands before SCMD_STATE_INFLIGHT is cleared by scsi_dec_host_busy(), resulting in neither waking the error handler task. This needs the call to scsi_host_busy() to be moved after host_failed is incremented to close the race condition.
Product status
6eb045e092efefafc6687409a6fa6d1dabf0fb69 (git) before cc872e35c0df80062abc71268d690a2f749e542e
6eb045e092efefafc6687409a6fa6d1dabf0fb69 (git) before 6d9a367be356101963c249ebf10ea10b32886607
6eb045e092efefafc6687409a6fa6d1dabf0fb69 (git) before 9fdc6f28d5e81350ab1d2cac8389062bd09e61e1
6eb045e092efefafc6687409a6fa6d1dabf0fb69 (git) before 64ae21b9c4f0c7e60cf47a53fa7ab68852079ef0
6eb045e092efefafc6687409a6fa6d1dabf0fb69 (git) before 219f009ebfd1ef3970888ee9eef4c8a06357f862
6eb045e092efefafc6687409a6fa6d1dabf0fb69 (git) before fe2f8ad6f0999db3b318359a01ee0108c703a8c3
5.5
Any version before 5.5
5.10.249 (semver)
6.1.162 (semver)
6.6.122 (semver)
6.12.68 (semver)
6.18.8 (semver)
6.19 (original_commit_for_fix)
References
git.kernel.org/...c/cc872e35c0df80062abc71268d690a2f749e542e
git.kernel.org/...c/6d9a367be356101963c249ebf10ea10b32886607
git.kernel.org/...c/9fdc6f28d5e81350ab1d2cac8389062bd09e61e1
git.kernel.org/...c/64ae21b9c4f0c7e60cf47a53fa7ab68852079ef0
git.kernel.org/...c/219f009ebfd1ef3970888ee9eef4c8a06357f862
git.kernel.org/...c/fe2f8ad6f0999db3b318359a01ee0108c703a8c3