From: drh <>
Date: Mon, 5 Dec 2022 14:23:06 +0000 (+0000)
Subject: Fix a problem in the memdb vfs xLock() function allowing clients to upgrade to EXCLUS... 
X-Git-Tag: version-3.40.1~16
X-Git-Url: http://git.ipfire.org/?a=commitdiff_plain;h=51802270d0e3f9b098f5bff1e58099f0342159ac;p=thirdparty%2Fsqlite.git

Fix a problem in the memdb vfs xLock() function allowing clients to upgrade to EXCLUSIVE locks when other connections are holding SHARED.

FossilOrigin-Name: d18cce37b5b73bb2a4f28eb1b55eb2c3ffe1fc23c921c13170af3d74a549f48e
---

diff --git a/manifest b/manifest
index 36fab0319d..37452bbc6e 100644
--- a/manifest
+++ b/manifest
@@ -1,5 +1,5 @@
-C Regenerate\sthe\sconfigure\sscript\sso\sthat\sit\sincludes\sthe\scorrect\spatch\snumber.
-D 2022-12-05T14:20:57.825
+C Fix\sa\sproblem\sin\sthe\smemdb\svfs\sxLock()\sfunction\sallowing\sclients\sto\supgrade\sto\sEXCLUSIVE\slocks\swhen\sother\sconnections\sare\sholding\sSHARED.
+D 2022-12-05T14:23:06.852
 F .fossil-settings/empty-dirs dbb81e8fc0401ac46a1491ab34a7f2c7c0452f2f06b54ebb845d024ca8283ef1
 F .fossil-settings/ignore-glob 35175cdfcf539b2318cb04a9901442804be81cd677d8b889fcc9149c21f239ea
 F LICENSE.md df5091916dbb40e6e9686186587125e1b2ff51f022cc334e886c19a0e9982724
@@ -607,7 +607,7 @@ F src/mem1.c c12a42539b1ba105e3707d0e628ad70e611040d8f5e38cf942cee30c867083de
 F src/mem2.c c8bfc9446fd0798bddd495eb5d9dbafa7d4b7287d8c22d50a83ac9daa26d8a75
 F src/mem3.c 30301196cace2a085cbedee1326a49f4b26deff0af68774ca82c1f7c06fda4f6
 F src/mem5.c 5a3dbd8ac8a6501152a4fc1fcae9b0900c2d7eb0589c4ec7456fdde15725a26c
-F src/memdb.c c2dc88f97c410eb68a24468344b65526685e18354ddfd15906750c1eaf9dc2dd
+F src/memdb.c 281e5cea3368b6ada342da37c4cffa88060cb4ee803caf9d83f2422a5ced512d
 F src/memjournal.c c283c6c95d940eb9dc70f1863eef3ee40382dbd35e5a1108026e7817c206e8a0
 F src/msvc.h 3a15918220367a8876be3fa4f2abe423a861491e84b864fb2b7426bf022a28f8
 F src/mutex.c 5e3409715552348732e97b9194abe92fdfcd934cfb681df4ba0ab87ac6c18d25
@@ -2055,8 +2055,9 @@ F vsixtest/vsixtest.tcl 6a9a6ab600c25a91a7acc6293828957a386a8a93
 F vsixtest/vsixtest.vcxproj.data 2ed517e100c66dc455b492e1a33350c1b20fbcdc
 F vsixtest/vsixtest.vcxproj.filters 37e51ffedcdb064aad6ff33b6148725226cd608e
 F vsixtest/vsixtest_TemporaryKey.pfx e5b1b036facdb453873e7084e1cae9102ccc67a0
-P b344f33d16213cd8861903b9e3e8efe9b4aaf36e742006e32b67b8ff4d5f8b7d
-R b04783b8d5555affda4a0fb27de8501c
+P e2ae2ea195593f142e4a0c23b7d18381efcaa4114b1de04a97543ac264cd527e
+Q +15f0be8a640e7bfa4130edd4650a745337bd96083b119a1553f9abf9ff066806
+R d07b70ffc1cbebb6ce31a34bad8efad2
 U drh
-Z 88487a218fbbe5a11095f4905c42c222
+Z 5db10dbe2408f5c4d9fdadd54b894daf
 # Remove this line to create a well-formed Fossil manifest.
diff --git a/manifest.uuid b/manifest.uuid
index 026f6f467b..2e6a001cc3 100644
--- a/manifest.uuid
+++ b/manifest.uuid
@@ -1 +1 @@
-e2ae2ea195593f142e4a0c23b7d18381efcaa4114b1de04a97543ac264cd527e
\ No newline at end of file
+d18cce37b5b73bb2a4f28eb1b55eb2c3ffe1fc23c921c13170af3d74a549f48e
\ No newline at end of file
diff --git a/src/memdb.c b/src/memdb.c
index 31b2324b93..2b9a51d72c 100644
--- a/src/memdb.c
+++ b/src/memdb.c
@@ -371,9 +371,22 @@ static int memdbLock(sqlite3_file *pFile, int eLock){
   if( eLock==pThis->eLock ) return SQLITE_OK;
   memdbEnter(p);
   if( eLock>SQLITE_LOCK_SHARED ){
+    assert( pThis->eLock>=SQLITE_LOCK_SHARED );
     if( p->mFlags & SQLITE_DESERIALIZE_READONLY ){
       rc = SQLITE_READONLY;
+    }else if( eLock==SQLITE_LOCK_EXCLUSIVE ){
+      /* Taking an EXCLUSIVE lock. Fail if we only have SHARED and any
+      ** other client has any kind of write-lock. Also fail if any other
+      ** client is holding read-lock. */
+      if( pThis->eLock<=SQLITE_LOCK_SHARED && p->nWrLock ){
+        rc = SQLITE_BUSY;
+      }else if( p->nRdLock>1 ){
+        rc = SQLITE_BUSY;
+      }
+      p->nWrLock = 1;
     }else if( pThis->eLock<=SQLITE_LOCK_SHARED ){
+      /* Upgrading to RESERVED or PENDING from SHARED. Fail if any other
+      ** client has a write-lock of any kind.  */
       if( p->nWrLock ){
         rc = SQLITE_BUSY;
       }else{