diff options
| author | Nathan Bossart <nathan@postgresql.org> | 2024-01-22 20:44:38 -0600 |
|---|---|---|
| committer | Nathan Bossart <nathan@postgresql.org> | 2024-01-22 20:44:38 -0600 |
| commit | 4372adfa24f2f5ddc587317d634b5389bd764106 (patch) | |
| tree | 3fac41ae7e0a99b9c4498157bb4f4e82e64bb947 /src | |
| parent | cdd863480c27b406ac14e94f1fe122b98ea562b4 (diff) | |
Fix possible NULL pointer dereference in GetNamedDSMSegment().
GetNamedDSMSegment() doesn't check whether dsm_attach() returns
NULL, which creates the possibility of a NULL pointer dereference
soon after. To fix, emit an ERROR if dsm_attach() returns NULL.
This shouldn't happen, but it would be nice to avoid a segfault if
it does. In passing, tidy up the surrounding code.
Reported-by: Tom Lane
Reviewed-by: Michael Paquier, Bharath Rupireddy
Discussion: https://postgr.es/m/3348869.1705854106%40sss.pgh.pa.us
Diffstat (limited to 'src')
| -rw-r--r-- | src/backend/storage/ipc/dsm_registry.c | 21 |
1 files changed, 12 insertions, 9 deletions
diff --git a/src/backend/storage/ipc/dsm_registry.c b/src/backend/storage/ipc/dsm_registry.c index ac11f51375e..c1781736532 100644 --- a/src/backend/storage/ipc/dsm_registry.c +++ b/src/backend/storage/ipc/dsm_registry.c @@ -177,19 +177,22 @@ GetNamedDSMSegment(const char *name, size_t size, (errmsg("requested DSM segment size does not match size of " "existing segment"))); } - else if (!dsm_find_mapping(entry->handle)) + else { - /* Attach to existing segment. */ - dsm_segment *seg = dsm_attach(entry->handle); + dsm_segment *seg = dsm_find_mapping(entry->handle); + + /* If the existing segment is not already attached, attach it now. */ + if (seg == NULL) + { + seg = dsm_attach(entry->handle); + if (seg == NULL) + elog(ERROR, "could not map dynamic shared memory segment"); + + dsm_pin_mapping(seg); + } - dsm_pin_mapping(seg); ret = dsm_segment_address(seg); } - else - { - /* Return address of an already-attached segment. */ - ret = dsm_segment_address(dsm_find_mapping(entry->handle)); - } dshash_release_lock(dsm_registry_table, entry); MemoryContextSwitchTo(oldcontext); |