103 lines
3.6 KiB
Diff
103 lines
3.6 KiB
Diff
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From 2075b2b96208ac8b989ca316dcdd674c3f488e2b Mon Sep 17 00:00:00 2001
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From: Martijn Dekker <martijn@inlv.org>
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Date: Thu, 28 Dec 2023 04:02:28 +0000
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Subject: [PATCH] Subject: [PATCH] Fix crash on failure to trim ~/.sh_history
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@vmihalko writes:
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> We were able to reproduce an old issue mentioned in
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> https://bugzilla.redhat.com/show_bug.cgi?id=1885399 using the
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> latest version of ksh. The corresponding code has not changed
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> much in the past few years.
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>
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> To provide further explanation, the problem arises when a user's
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> .sh_history file grows to a size that triggers the hist_trim
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> function, but the user lacks (after the creation of .sh_history)
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> the necessary write permissions to their $HOME directory. As a
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> result, ksh becomes stuck in a recursive loop between the
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> sh_histinit(src/cmd/ksh93/edit/history.c#L203) function and the
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> hist_trim(src/cmd/ksh93/edit/history.c#L417) function.
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>
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> Conditions for reproduction:
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>
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> 1. The size of the .sh_history file is larger than the HIST_MAX
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> limit. (src/cmd/ksh93/edit/history.c, line 325)
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> 2. .sh_history file has not been changed in the HIST_RECENT
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> seconds (src/cmd/ksh93/edit/history.c, line 406)
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> 3. The user does not have permission to write to the $HOME
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> directory.
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src/cmd/ksh93/edit/history.c: hist_trim():
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- Print a warning and return if unlink(2) fails. The warning tells
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the user to check the history file's parent directory is
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writable. This is the best I realistically do for now, because
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this function's basic method assumes a writable parent directory.
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- The temp file fallback is deleted because it's fundamentally
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flawed: it assumes the temp file is made on the same volume as
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the history file and can simply be rename(2)'d in place. Even
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on systems where this is the case, it doesn't appear to be
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working correctly, but this is not worth looking into.
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Resolves: https://github.com/ksh93/ksh/issues/695
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---
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src/cmd/ksh93/edit/history.c | 34 ++++------------------------------
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1 file changed, 4 insertions(+), 30 deletions(-)
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diff --git a/src/cmd/ksh93/edit/history.c b/src/cmd/ksh93/edit/history.c
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index 1f6cd7c..0ed8e8a 100644
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--- a/src/cmd/ksh93/edit/history.c
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+++ b/src/cmd/ksh93/edit/history.c
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@@ -461,34 +461,13 @@ static History_t* hist_trim(History_t *hp, int n)
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register char *cp;
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register int incmd=1, c=0;
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register History_t *hist_new, *hist_old = hp;
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- char *buff, *endbuff, *tmpname=0;
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+ char *buff, *endbuff;
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off_t oldp,newp;
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struct stat statb;
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- unlink(hist_old->histname);
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- if(access(hist_old->histname,F_OK) >= 0)
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+ if(unlink(hist_old->histname) < 0)
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{
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- /* The unlink can fail on windows 95 */
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- int fd;
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- char *last, *name=hist_old->histname;
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- close(sffileno(hist_old->histfp));
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- tmpname = (char*)malloc(strlen(name)+14);
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- if(last = strrchr(name,'/'))
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- {
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- *last = 0;
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- pathtmp(tmpname,name,"hist",NIL(int*));
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- *last = '/';
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- }
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- else
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- pathtmp(tmpname,".","hist",NIL(int*));
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- if(rename(name,tmpname) < 0)
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- {
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- free(tmpname);
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- tmpname = name;
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- }
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- fd = open(tmpname,O_RDONLY);
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- sfsetfd(hist_old->histfp,fd);
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- if(tmpname==name)
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- tmpname = 0;
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+ errormsg(SH_DICT,ERROR_warn(0),"cannot trim history file %s; make sure parent directory is writable",hist_old->histname);
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+ return hist_ptr = hist_old;
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}
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hist_ptr = 0;
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if(fstat(sffileno(hist_old->histfp),&statb)>=0)
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@@ -543,11 +522,6 @@ static History_t* hist_trim(History_t *hp, int n)
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}
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hist_cancel(hist_new);
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sfclose(hist_old->histfp);
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- if(tmpname)
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- {
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- unlink(tmpname);
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- free(tmpname);
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- }
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free((char*)hist_old);
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return hist_ptr = hist_new;
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}
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--
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2.42.0
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