Experimental Physics and
Industrial Control System

Still present on 3.15 and 3.16 branches/heads

On 05/10/2016 07:10 PM, Till Straumann wrote:

Dehong reported the following bug:

In order to convert between legacy and more 'modern' representation of
data with at least DBR_STATUS auxiliary information

db_access.c: db_get_field_and_count()

calls dbGetField() twice; a first time to retrieve the auxiliary information

(status, timestamps, ...) and a second time to fetch data.

Since the underlying record is not locked across the two calls to dbGetField()

the record could be processed in between and render the auxiliary data
invalid/obsolete.

Proposed fix:

AFAIK, dbScanLock() supports recursion and therefore the easiest
fix would be acquiring the record lock within db_get_field_and_count()

RFC
- Till

PS: the bug seems to still be present in the 3.14 branch head

References:

Race condition in db_get_field_and_count() (3.14.12) Till Straumann

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